diff --git a/examples/app-pytorch/client_low_level.py b/examples/app-pytorch/client_low_level.py
index feea1ee658fe..19268ff84ba4 100644
--- a/examples/app-pytorch/client_low_level.py
+++ b/examples/app-pytorch/client_low_level.py
@@ -20,16 +20,16 @@ def hello_world_mod(msg, ctx, call_next) -> Message:
 @app.train()
 def train(msg: Message, ctx: Context):
     print("`train` is not implemented, echoing original message")
-    return msg.create_reply(msg.content, ttl="")
+    return msg.create_reply(msg.content)
 
 
 @app.evaluate()
 def eval(msg: Message, ctx: Context):
     print("`evaluate` is not implemented, echoing original message")
-    return msg.create_reply(msg.content, ttl="")
+    return msg.create_reply(msg.content)
 
 
 @app.query()
 def query(msg: Message, ctx: Context):
     print("`query` is not implemented, echoing original message")
-    return msg.create_reply(msg.content, ttl="")
+    return msg.create_reply(msg.content)
diff --git a/examples/app-pytorch/server_custom.py b/examples/app-pytorch/server_custom.py
index 51ac8a5c006c..67c1bce99c55 100644
--- a/examples/app-pytorch/server_custom.py
+++ b/examples/app-pytorch/server_custom.py
@@ -13,6 +13,7 @@
     Message,
     MessageType,
     Metrics,
+    DEFAULT_TTL,
 )
 from flwr.common.recordset_compat import fitins_to_recordset, recordset_to_fitres
 from flwr.server import Driver, History
@@ -89,7 +90,7 @@ def main(driver: Driver, context: Context) -> None:
                 message_type=MessageType.TRAIN,
                 dst_node_id=node_id,
                 group_id=str(server_round),
-                ttl="",
+                ttl=DEFAULT_TTL,
             )
             messages.append(message)
 
diff --git a/examples/app-pytorch/server_low_level.py b/examples/app-pytorch/server_low_level.py
index 560babac1b95..7ab79a4a04c8 100644
--- a/examples/app-pytorch/server_low_level.py
+++ b/examples/app-pytorch/server_low_level.py
@@ -3,7 +3,15 @@
 import time
 
 import flwr as fl
-from flwr.common import Context, NDArrays, Message, MessageType, Metrics, RecordSet
+from flwr.common import (
+    Context,
+    NDArrays,
+    Message,
+    MessageType,
+    Metrics,
+    RecordSet,
+    DEFAULT_TTL,
+)
 from flwr.server import Driver
 
 
@@ -30,7 +38,7 @@ def main(driver: Driver, context: Context) -> None:
                 message_type=MessageType.TRAIN,
                 dst_node_id=node_id,
                 group_id=str(server_round),
-                ttl="",
+                ttl=DEFAULT_TTL,
             )
             messages.append(message)
 
diff --git a/examples/llm-flowertune/requirements.txt b/examples/llm-flowertune/requirements.txt
index c7ff57b403f7..196531c99b92 100644
--- a/examples/llm-flowertune/requirements.txt
+++ b/examples/llm-flowertune/requirements.txt
@@ -6,3 +6,4 @@ bitsandbytes==0.41.3
 scipy==1.11.2
 peft==0.4.0
 fschat[model_worker,webui]==0.2.35
+transformers==4.38.1
diff --git a/src/proto/flwr/proto/fleet.proto b/src/proto/flwr/proto/fleet.proto
index c900a3b1148d..fcb301181f5a 100644
--- a/src/proto/flwr/proto/fleet.proto
+++ b/src/proto/flwr/proto/fleet.proto
@@ -23,6 +23,7 @@ import "flwr/proto/task.proto";
 service Fleet {
   rpc CreateNode(CreateNodeRequest) returns (CreateNodeResponse) {}
   rpc DeleteNode(DeleteNodeRequest) returns (DeleteNodeResponse) {}
+  rpc Ping(PingRequest) returns (PingResponse) {}
 
   // Retrieve one or more tasks, if possible
   //
@@ -43,6 +44,10 @@ message CreateNodeResponse { Node node = 1; }
 message DeleteNodeRequest { Node node = 1; }
 message DeleteNodeResponse {}
 
+// Ping messages
+message PingRequest { Node node = 1; }
+message PingResponse { bool success = 1; }
+
 // PullTaskIns messages
 message PullTaskInsRequest {
   Node node = 1;
diff --git a/src/proto/flwr/proto/task.proto b/src/proto/flwr/proto/task.proto
index 423df76f1335..4c86ebae9562 100644
--- a/src/proto/flwr/proto/task.proto
+++ b/src/proto/flwr/proto/task.proto
@@ -27,7 +27,7 @@ message Task {
   Node consumer = 2;
   string created_at = 3;
   string delivered_at = 4;
-  string ttl = 5;
+  double ttl = 5;
   repeated string ancestry = 6;
   string task_type = 7;
   RecordSet recordset = 8;
diff --git a/src/py/flwr/client/client_app.py b/src/py/flwr/client/client_app.py
index ad7a01326991..0b56219807c6 100644
--- a/src/py/flwr/client/client_app.py
+++ b/src/py/flwr/client/client_app.py
@@ -115,7 +115,7 @@ def train(self) -> Callable[[ClientAppCallable], ClientAppCallable]:
         >>> def train(message: Message, context: Context) -> Message:
         >>>    print("ClientApp training running")
         >>>    # Create and return an echo reply message
-        >>>    return message.create_reply(content=message.content(), ttl="")
+        >>>    return message.create_reply(content=message.content())
         """
 
         def train_decorator(train_fn: ClientAppCallable) -> ClientAppCallable:
@@ -143,7 +143,7 @@ def evaluate(self) -> Callable[[ClientAppCallable], ClientAppCallable]:
         >>> def evaluate(message: Message, context: Context) -> Message:
         >>>    print("ClientApp evaluation running")
         >>>    # Create and return an echo reply message
-        >>>    return message.create_reply(content=message.content(), ttl="")
+        >>>    return message.create_reply(content=message.content())
         """
 
         def evaluate_decorator(evaluate_fn: ClientAppCallable) -> ClientAppCallable:
@@ -171,7 +171,7 @@ def query(self) -> Callable[[ClientAppCallable], ClientAppCallable]:
         >>> def query(message: Message, context: Context) -> Message:
         >>>    print("ClientApp query running")
         >>>    # Create and return an echo reply message
-        >>>    return message.create_reply(content=message.content(), ttl="")
+        >>>    return message.create_reply(content=message.content())
         """
 
         def query_decorator(query_fn: ClientAppCallable) -> ClientAppCallable:
@@ -218,7 +218,7 @@ def _registration_error(fn_name: str) -> ValueError:
         >>>    print("ClientApp {fn_name} running")
         >>>    # Create and return an echo reply message
         >>>    return message.create_reply(
-        >>>        content=message.content(), ttl=""
+        >>>        content=message.content()
         >>>    )
         """,
     )
diff --git a/src/py/flwr/client/grpc_client/connection.py b/src/py/flwr/client/grpc_client/connection.py
index 163a58542c9e..4431b53d2592 100644
--- a/src/py/flwr/client/grpc_client/connection.py
+++ b/src/py/flwr/client/grpc_client/connection.py
@@ -23,6 +23,7 @@
 from typing import Callable, Iterator, Optional, Tuple, Union, cast
 
 from flwr.common import (
+    DEFAULT_TTL,
     GRPC_MAX_MESSAGE_LENGTH,
     ConfigsRecord,
     Message,
@@ -180,7 +181,7 @@ def receive() -> Message:
                 dst_node_id=0,
                 reply_to_message="",
                 group_id="",
-                ttl="",
+                ttl=DEFAULT_TTL,
                 message_type=message_type,
             ),
             content=recordset,
diff --git a/src/py/flwr/client/grpc_client/connection_test.py b/src/py/flwr/client/grpc_client/connection_test.py
index b7737f511a2a..061e7d4377a0 100644
--- a/src/py/flwr/client/grpc_client/connection_test.py
+++ b/src/py/flwr/client/grpc_client/connection_test.py
@@ -23,7 +23,7 @@
 
 import grpc
 
-from flwr.common import ConfigsRecord, Message, Metadata, RecordSet
+from flwr.common import DEFAULT_TTL, ConfigsRecord, Message, Metadata, RecordSet
 from flwr.common import recordset_compat as compat
 from flwr.common.constant import MessageTypeLegacy
 from flwr.common.retry_invoker import RetryInvoker, exponential
@@ -50,7 +50,7 @@
         dst_node_id=0,
         reply_to_message="",
         group_id="",
-        ttl="",
+        ttl=DEFAULT_TTL,
         message_type=MessageTypeLegacy.GET_PROPERTIES,
     ),
     content=compat.getpropertiesres_to_recordset(
@@ -65,7 +65,7 @@
         dst_node_id=0,
         reply_to_message="",
         group_id="",
-        ttl="",
+        ttl=DEFAULT_TTL,
         message_type="reconnect",
     ),
     content=RecordSet(configs_records={"config": ConfigsRecord({"reason": 0})}),
diff --git a/src/py/flwr/client/message_handler/message_handler.py b/src/py/flwr/client/message_handler/message_handler.py
index 9a5d70b1ac4d..87014f436cf7 100644
--- a/src/py/flwr/client/message_handler/message_handler.py
+++ b/src/py/flwr/client/message_handler/message_handler.py
@@ -81,7 +81,7 @@ def handle_control_message(message: Message) -> Tuple[Optional[Message], int]:
         reason = cast(int, disconnect_msg.disconnect_res.reason)
         recordset = RecordSet()
         recordset.configs_records["config"] = ConfigsRecord({"reason": reason})
-        out_message = message.create_reply(recordset, ttl="")
+        out_message = message.create_reply(recordset)
         # Return TaskRes and sleep duration
         return out_message, sleep_duration
 
@@ -143,7 +143,7 @@ def handle_legacy_message_from_msgtype(
         raise ValueError(f"Invalid message type: {message_type}")
 
     # Return Message
-    return message.create_reply(out_recordset, ttl="")
+    return message.create_reply(out_recordset)
 
 
 def _reconnect(
diff --git a/src/py/flwr/client/message_handler/message_handler_test.py b/src/py/flwr/client/message_handler/message_handler_test.py
index eaf16f7dc993..e3f6487421cc 100644
--- a/src/py/flwr/client/message_handler/message_handler_test.py
+++ b/src/py/flwr/client/message_handler/message_handler_test.py
@@ -23,6 +23,7 @@
 from flwr.client import Client
 from flwr.client.typing import ClientFn
 from flwr.common import (
+    DEFAULT_TTL,
     Code,
     Context,
     EvaluateIns,
@@ -131,7 +132,7 @@ def test_client_without_get_properties() -> None:
             src_node_id=0,
             dst_node_id=1123,
             reply_to_message="",
-            ttl="",
+            ttl=DEFAULT_TTL,
             message_type=MessageTypeLegacy.GET_PROPERTIES,
         ),
         content=recordset,
@@ -161,7 +162,7 @@ def test_client_without_get_properties() -> None:
             src_node_id=1123,
             dst_node_id=0,
             reply_to_message=message.metadata.message_id,
-            ttl="",
+            ttl=DEFAULT_TTL,
             message_type=MessageTypeLegacy.GET_PROPERTIES,
         ),
         content=expected_rs,
@@ -184,7 +185,7 @@ def test_client_with_get_properties() -> None:
             src_node_id=0,
             dst_node_id=1123,
             reply_to_message="",
-            ttl="",
+            ttl=DEFAULT_TTL,
             message_type=MessageTypeLegacy.GET_PROPERTIES,
         ),
         content=recordset,
@@ -214,7 +215,7 @@ def test_client_with_get_properties() -> None:
             src_node_id=1123,
             dst_node_id=0,
             reply_to_message=message.metadata.message_id,
-            ttl="",
+            ttl=DEFAULT_TTL,
             message_type=MessageTypeLegacy.GET_PROPERTIES,
         ),
         content=expected_rs,
@@ -237,7 +238,7 @@ def setUp(self) -> None:
             dst_node_id=20,
             reply_to_message="",
             group_id="group1",
-            ttl="60",
+            ttl=DEFAULT_TTL,
             message_type="mock",
         )
         self.valid_out_metadata = Metadata(
@@ -247,7 +248,7 @@ def setUp(self) -> None:
             dst_node_id=10,
             reply_to_message="qwerty",
             group_id="group1",
-            ttl="60",
+            ttl=DEFAULT_TTL,
             message_type="mock",
         )
         self.common_content = RecordSet()
diff --git a/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod.py b/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod.py
index 989d5f6e1361..5b196ad84321 100644
--- a/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod.py
+++ b/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod.py
@@ -187,7 +187,7 @@ def secaggplus_mod(
 
     # Return message
     out_content.configs_records[RECORD_KEY_CONFIGS] = ConfigsRecord(res, False)
-    return msg.create_reply(out_content, ttl="")
+    return msg.create_reply(out_content)
 
 
 def check_stage(current_stage: str, configs: ConfigsRecord) -> None:
diff --git a/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod_test.py b/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod_test.py
index db5ed67c02a4..36844a2983a1 100644
--- a/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod_test.py
+++ b/src/py/flwr/client/mod/secure_aggregation/secaggplus_mod_test.py
@@ -19,7 +19,14 @@
 from typing import Callable, Dict, List
 
 from flwr.client.mod import make_ffn
-from flwr.common import ConfigsRecord, Context, Message, Metadata, RecordSet
+from flwr.common import (
+    DEFAULT_TTL,
+    ConfigsRecord,
+    Context,
+    Message,
+    Metadata,
+    RecordSet,
+)
 from flwr.common.constant import MessageType
 from flwr.common.secure_aggregation.secaggplus_constants import (
     RECORD_KEY_CONFIGS,
@@ -38,7 +45,7 @@ def get_test_handler(
     """."""
 
     def empty_ffn(_msg: Message, _2: Context) -> Message:
-        return _msg.create_reply(RecordSet(), ttl="")
+        return _msg.create_reply(RecordSet())
 
     app = make_ffn(empty_ffn, [secaggplus_mod])
 
@@ -51,7 +58,7 @@ def func(configs: Dict[str, ConfigsRecordValues]) -> ConfigsRecord:
                 dst_node_id=123,
                 reply_to_message="",
                 group_id="",
-                ttl="",
+                ttl=DEFAULT_TTL,
                 message_type=MessageType.TRAIN,
             ),
             content=RecordSet(
diff --git a/src/py/flwr/client/mod/utils_test.py b/src/py/flwr/client/mod/utils_test.py
index e588b8b53b3b..4676a2c02c4b 100644
--- a/src/py/flwr/client/mod/utils_test.py
+++ b/src/py/flwr/client/mod/utils_test.py
@@ -20,6 +20,7 @@
 
 from flwr.client.typing import ClientAppCallable, Mod
 from flwr.common import (
+    DEFAULT_TTL,
     ConfigsRecord,
     Context,
     Message,
@@ -84,7 +85,7 @@ def _get_dummy_flower_message() -> Message:
             src_node_id=0,
             dst_node_id=0,
             reply_to_message="",
-            ttl="",
+            ttl=DEFAULT_TTL,
             message_type="mock",
         ),
     )
diff --git a/src/py/flwr/common/__init__.py b/src/py/flwr/common/__init__.py
index 9f9ff7ebc68a..2fb98c82dd6f 100644
--- a/src/py/flwr/common/__init__.py
+++ b/src/py/flwr/common/__init__.py
@@ -22,6 +22,7 @@
 from .grpc import GRPC_MAX_MESSAGE_LENGTH
 from .logger import configure as configure
 from .logger import log as log
+from .message import DEFAULT_TTL
 from .message import Error as Error
 from .message import Message as Message
 from .message import Metadata as Metadata
@@ -87,6 +88,7 @@
     "Message",
     "MessageType",
     "MessageTypeLegacy",
+    "DEFAULT_TTL",
     "Metadata",
     "Metrics",
     "MetricsAggregationFn",
diff --git a/src/py/flwr/common/message.py b/src/py/flwr/common/message.py
index 88cf750f1a94..25607179764d 100644
--- a/src/py/flwr/common/message.py
+++ b/src/py/flwr/common/message.py
@@ -20,6 +20,8 @@
 
 from .record import RecordSet
 
+DEFAULT_TTL = 3600
+
 
 @dataclass
 class Metadata:  # pylint: disable=too-many-instance-attributes
@@ -40,8 +42,8 @@ class Metadata:  # pylint: disable=too-many-instance-attributes
     group_id : str
         An identifier for grouping messages. In some settings,
         this is used as the FL round.
-    ttl : str
-        Time-to-live for this message.
+    ttl : float
+        Time-to-live for this message in seconds.
     message_type : str
         A string that encodes the action to be executed on
         the receiving end.
@@ -57,7 +59,7 @@ class Metadata:  # pylint: disable=too-many-instance-attributes
     _dst_node_id: int
     _reply_to_message: str
     _group_id: str
-    _ttl: str
+    _ttl: float
     _message_type: str
     _partition_id: int | None
 
@@ -69,7 +71,7 @@ def __init__(  # pylint: disable=too-many-arguments
         dst_node_id: int,
         reply_to_message: str,
         group_id: str,
-        ttl: str,
+        ttl: float,
         message_type: str,
         partition_id: int | None = None,
     ) -> None:
@@ -124,12 +126,12 @@ def group_id(self, value: str) -> None:
         self._group_id = value
 
     @property
-    def ttl(self) -> str:
+    def ttl(self) -> float:
         """Time-to-live for this message."""
         return self._ttl
 
     @ttl.setter
-    def ttl(self, value: str) -> None:
+    def ttl(self, value: float) -> None:
         """Set ttl."""
         self._ttl = value
 
@@ -266,7 +268,7 @@ def has_error(self) -> bool:
         """Return True if message has an error, else False."""
         return self._error is not None
 
-    def _create_reply_metadata(self, ttl: str) -> Metadata:
+    def _create_reply_metadata(self, ttl: float) -> Metadata:
         """Construct metadata for a reply message."""
         return Metadata(
             run_id=self.metadata.run_id,
@@ -283,7 +285,7 @@ def _create_reply_metadata(self, ttl: str) -> Metadata:
     def create_error_reply(
         self,
         error: Error,
-        ttl: str,
+        ttl: float,
     ) -> Message:
         """Construct a reply message indicating an error happened.
 
@@ -291,14 +293,14 @@ def create_error_reply(
         ----------
         error : Error
             The error that was encountered.
-        ttl : str
-            Time-to-live for this message.
+        ttl : float
+            Time-to-live for this message in seconds.
         """
         # Create reply with error
         message = Message(metadata=self._create_reply_metadata(ttl), error=error)
         return message
 
-    def create_reply(self, content: RecordSet, ttl: str) -> Message:
+    def create_reply(self, content: RecordSet, ttl: float | None = None) -> Message:
         """Create a reply to this message with specified content and TTL.
 
         The method generates a new `Message` as a reply to this message.
@@ -309,14 +311,18 @@ def create_reply(self, content: RecordSet, ttl: str) -> Message:
         ----------
         content : RecordSet
             The content for the reply message.
-        ttl : str
-            Time-to-live for this message.
+        ttl : Optional[float] (default: None)
+            Time-to-live for this message in seconds. If unset, it will use
+            the `common.DEFAULT_TTL` value.
 
         Returns
         -------
         Message
             A new `Message` instance representing the reply.
         """
+        if ttl is None:
+            ttl = DEFAULT_TTL
+
         return Message(
             metadata=self._create_reply_metadata(ttl),
             content=content,
diff --git a/src/py/flwr/common/serde_test.py b/src/py/flwr/common/serde_test.py
index 8596e5d2f330..fc12ce95328f 100644
--- a/src/py/flwr/common/serde_test.py
+++ b/src/py/flwr/common/serde_test.py
@@ -219,7 +219,7 @@ def metadata(self) -> Metadata:
             src_node_id=self.rng.randint(0, 1 << 63),
             dst_node_id=self.rng.randint(0, 1 << 63),
             reply_to_message=self.get_str(64),
-            ttl=self.get_str(10),
+            ttl=self.rng.randint(1, 1 << 30),
             message_type=self.get_str(10),
         )
 
diff --git a/src/py/flwr/proto/fleet_pb2.py b/src/py/flwr/proto/fleet_pb2.py
index e8443c296f0c..dbf64fb850a5 100644
--- a/src/py/flwr/proto/fleet_pb2.py
+++ b/src/py/flwr/proto/fleet_pb2.py
@@ -16,7 +16,7 @@
 from flwr.proto import task_pb2 as flwr_dot_proto_dot_task__pb2
 
 
-DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x16\x66lwr/proto/fleet.proto\x12\nflwr.proto\x1a\x15\x66lwr/proto/node.proto\x1a\x15\x66lwr/proto/task.proto\"\x13\n\x11\x43reateNodeRequest\"4\n\x12\x43reateNodeResponse\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\"3\n\x11\x44\x65leteNodeRequest\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\"\x14\n\x12\x44\x65leteNodeResponse\"F\n\x12PullTaskInsRequest\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\x12\x10\n\x08task_ids\x18\x02 \x03(\t\"k\n\x13PullTaskInsResponse\x12(\n\treconnect\x18\x01 \x01(\x0b\x32\x15.flwr.proto.Reconnect\x12*\n\rtask_ins_list\x18\x02 \x03(\x0b\x32\x13.flwr.proto.TaskIns\"@\n\x12PushTaskResRequest\x12*\n\rtask_res_list\x18\x01 \x03(\x0b\x32\x13.flwr.proto.TaskRes\"\xae\x01\n\x13PushTaskResResponse\x12(\n\treconnect\x18\x01 \x01(\x0b\x32\x15.flwr.proto.Reconnect\x12=\n\x07results\x18\x02 \x03(\x0b\x32,.flwr.proto.PushTaskResResponse.ResultsEntry\x1a.\n\x0cResultsEntry\x12\x0b\n\x03key\x18\x01 \x01(\t\x12\r\n\x05value\x18\x02 \x01(\r:\x02\x38\x01\"\x1e\n\tReconnect\x12\x11\n\treconnect\x18\x01 \x01(\x04\x32\xc9\x02\n\x05\x46leet\x12M\n\nCreateNode\x12\x1d.flwr.proto.CreateNodeRequest\x1a\x1e.flwr.proto.CreateNodeResponse\"\x00\x12M\n\nDeleteNode\x12\x1d.flwr.proto.DeleteNodeRequest\x1a\x1e.flwr.proto.DeleteNodeResponse\"\x00\x12P\n\x0bPullTaskIns\x12\x1e.flwr.proto.PullTaskInsRequest\x1a\x1f.flwr.proto.PullTaskInsResponse\"\x00\x12P\n\x0bPushTaskRes\x12\x1e.flwr.proto.PushTaskResRequest\x1a\x1f.flwr.proto.PushTaskResResponse\"\x00\x62\x06proto3')
+DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x16\x66lwr/proto/fleet.proto\x12\nflwr.proto\x1a\x15\x66lwr/proto/node.proto\x1a\x15\x66lwr/proto/task.proto\"\x13\n\x11\x43reateNodeRequest\"4\n\x12\x43reateNodeResponse\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\"3\n\x11\x44\x65leteNodeRequest\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\"\x14\n\x12\x44\x65leteNodeResponse\"-\n\x0bPingRequest\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\"\x1f\n\x0cPingResponse\x12\x0f\n\x07success\x18\x01 \x01(\x08\"F\n\x12PullTaskInsRequest\x12\x1e\n\x04node\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\x12\x10\n\x08task_ids\x18\x02 \x03(\t\"k\n\x13PullTaskInsResponse\x12(\n\treconnect\x18\x01 \x01(\x0b\x32\x15.flwr.proto.Reconnect\x12*\n\rtask_ins_list\x18\x02 \x03(\x0b\x32\x13.flwr.proto.TaskIns\"@\n\x12PushTaskResRequest\x12*\n\rtask_res_list\x18\x01 \x03(\x0b\x32\x13.flwr.proto.TaskRes\"\xae\x01\n\x13PushTaskResResponse\x12(\n\treconnect\x18\x01 \x01(\x0b\x32\x15.flwr.proto.Reconnect\x12=\n\x07results\x18\x02 \x03(\x0b\x32,.flwr.proto.PushTaskResResponse.ResultsEntry\x1a.\n\x0cResultsEntry\x12\x0b\n\x03key\x18\x01 \x01(\t\x12\r\n\x05value\x18\x02 \x01(\r:\x02\x38\x01\"\x1e\n\tReconnect\x12\x11\n\treconnect\x18\x01 \x01(\x04\x32\x86\x03\n\x05\x46leet\x12M\n\nCreateNode\x12\x1d.flwr.proto.CreateNodeRequest\x1a\x1e.flwr.proto.CreateNodeResponse\"\x00\x12M\n\nDeleteNode\x12\x1d.flwr.proto.DeleteNodeRequest\x1a\x1e.flwr.proto.DeleteNodeResponse\"\x00\x12;\n\x04Ping\x12\x17.flwr.proto.PingRequest\x1a\x18.flwr.proto.PingResponse\"\x00\x12P\n\x0bPullTaskIns\x12\x1e.flwr.proto.PullTaskInsRequest\x1a\x1f.flwr.proto.PullTaskInsResponse\"\x00\x12P\n\x0bPushTaskRes\x12\x1e.flwr.proto.PushTaskResRequest\x1a\x1f.flwr.proto.PushTaskResResponse\"\x00\x62\x06proto3')
 
 _globals = globals()
 _builder.BuildMessageAndEnumDescriptors(DESCRIPTOR, _globals)
@@ -33,18 +33,22 @@
   _globals['_DELETENODEREQUEST']._serialized_end=210
   _globals['_DELETENODERESPONSE']._serialized_start=212
   _globals['_DELETENODERESPONSE']._serialized_end=232
-  _globals['_PULLTASKINSREQUEST']._serialized_start=234
-  _globals['_PULLTASKINSREQUEST']._serialized_end=304
-  _globals['_PULLTASKINSRESPONSE']._serialized_start=306
-  _globals['_PULLTASKINSRESPONSE']._serialized_end=413
-  _globals['_PUSHTASKRESREQUEST']._serialized_start=415
-  _globals['_PUSHTASKRESREQUEST']._serialized_end=479
-  _globals['_PUSHTASKRESRESPONSE']._serialized_start=482
-  _globals['_PUSHTASKRESRESPONSE']._serialized_end=656
-  _globals['_PUSHTASKRESRESPONSE_RESULTSENTRY']._serialized_start=610
-  _globals['_PUSHTASKRESRESPONSE_RESULTSENTRY']._serialized_end=656
-  _globals['_RECONNECT']._serialized_start=658
-  _globals['_RECONNECT']._serialized_end=688
-  _globals['_FLEET']._serialized_start=691
-  _globals['_FLEET']._serialized_end=1020
+  _globals['_PINGREQUEST']._serialized_start=234
+  _globals['_PINGREQUEST']._serialized_end=279
+  _globals['_PINGRESPONSE']._serialized_start=281
+  _globals['_PINGRESPONSE']._serialized_end=312
+  _globals['_PULLTASKINSREQUEST']._serialized_start=314
+  _globals['_PULLTASKINSREQUEST']._serialized_end=384
+  _globals['_PULLTASKINSRESPONSE']._serialized_start=386
+  _globals['_PULLTASKINSRESPONSE']._serialized_end=493
+  _globals['_PUSHTASKRESREQUEST']._serialized_start=495
+  _globals['_PUSHTASKRESREQUEST']._serialized_end=559
+  _globals['_PUSHTASKRESRESPONSE']._serialized_start=562
+  _globals['_PUSHTASKRESRESPONSE']._serialized_end=736
+  _globals['_PUSHTASKRESRESPONSE_RESULTSENTRY']._serialized_start=690
+  _globals['_PUSHTASKRESRESPONSE_RESULTSENTRY']._serialized_end=736
+  _globals['_RECONNECT']._serialized_start=738
+  _globals['_RECONNECT']._serialized_end=768
+  _globals['_FLEET']._serialized_start=771
+  _globals['_FLEET']._serialized_end=1161
 # @@protoc_insertion_point(module_scope)
diff --git a/src/py/flwr/proto/fleet_pb2.pyi b/src/py/flwr/proto/fleet_pb2.pyi
index 86bc358858d2..39edb61ca0d7 100644
--- a/src/py/flwr/proto/fleet_pb2.pyi
+++ b/src/py/flwr/proto/fleet_pb2.pyi
@@ -53,6 +53,31 @@ class DeleteNodeResponse(google.protobuf.message.Message):
         ) -> None: ...
 global___DeleteNodeResponse = DeleteNodeResponse
 
+class PingRequest(google.protobuf.message.Message):
+    """Ping messages"""
+    DESCRIPTOR: google.protobuf.descriptor.Descriptor
+    NODE_FIELD_NUMBER: builtins.int
+    @property
+    def node(self) -> flwr.proto.node_pb2.Node: ...
+    def __init__(self,
+        *,
+        node: typing.Optional[flwr.proto.node_pb2.Node] = ...,
+        ) -> None: ...
+    def HasField(self, field_name: typing_extensions.Literal["node",b"node"]) -> builtins.bool: ...
+    def ClearField(self, field_name: typing_extensions.Literal["node",b"node"]) -> None: ...
+global___PingRequest = PingRequest
+
+class PingResponse(google.protobuf.message.Message):
+    DESCRIPTOR: google.protobuf.descriptor.Descriptor
+    SUCCESS_FIELD_NUMBER: builtins.int
+    success: builtins.bool
+    def __init__(self,
+        *,
+        success: builtins.bool = ...,
+        ) -> None: ...
+    def ClearField(self, field_name: typing_extensions.Literal["success",b"success"]) -> None: ...
+global___PingResponse = PingResponse
+
 class PullTaskInsRequest(google.protobuf.message.Message):
     """PullTaskIns messages"""
     DESCRIPTOR: google.protobuf.descriptor.Descriptor
diff --git a/src/py/flwr/proto/fleet_pb2_grpc.py b/src/py/flwr/proto/fleet_pb2_grpc.py
index 2b53ec43e851..c31a4ec73f0e 100644
--- a/src/py/flwr/proto/fleet_pb2_grpc.py
+++ b/src/py/flwr/proto/fleet_pb2_grpc.py
@@ -24,6 +24,11 @@ def __init__(self, channel):
                 request_serializer=flwr_dot_proto_dot_fleet__pb2.DeleteNodeRequest.SerializeToString,
                 response_deserializer=flwr_dot_proto_dot_fleet__pb2.DeleteNodeResponse.FromString,
                 )
+        self.Ping = channel.unary_unary(
+                '/flwr.proto.Fleet/Ping',
+                request_serializer=flwr_dot_proto_dot_fleet__pb2.PingRequest.SerializeToString,
+                response_deserializer=flwr_dot_proto_dot_fleet__pb2.PingResponse.FromString,
+                )
         self.PullTaskIns = channel.unary_unary(
                 '/flwr.proto.Fleet/PullTaskIns',
                 request_serializer=flwr_dot_proto_dot_fleet__pb2.PullTaskInsRequest.SerializeToString,
@@ -51,6 +56,12 @@ def DeleteNode(self, request, context):
         context.set_details('Method not implemented!')
         raise NotImplementedError('Method not implemented!')
 
+    def Ping(self, request, context):
+        """Missing associated documentation comment in .proto file."""
+        context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+        context.set_details('Method not implemented!')
+        raise NotImplementedError('Method not implemented!')
+
     def PullTaskIns(self, request, context):
         """Retrieve one or more tasks, if possible
 
@@ -82,6 +93,11 @@ def add_FleetServicer_to_server(servicer, server):
                     request_deserializer=flwr_dot_proto_dot_fleet__pb2.DeleteNodeRequest.FromString,
                     response_serializer=flwr_dot_proto_dot_fleet__pb2.DeleteNodeResponse.SerializeToString,
             ),
+            'Ping': grpc.unary_unary_rpc_method_handler(
+                    servicer.Ping,
+                    request_deserializer=flwr_dot_proto_dot_fleet__pb2.PingRequest.FromString,
+                    response_serializer=flwr_dot_proto_dot_fleet__pb2.PingResponse.SerializeToString,
+            ),
             'PullTaskIns': grpc.unary_unary_rpc_method_handler(
                     servicer.PullTaskIns,
                     request_deserializer=flwr_dot_proto_dot_fleet__pb2.PullTaskInsRequest.FromString,
@@ -136,6 +152,23 @@ def DeleteNode(request,
             options, channel_credentials,
             insecure, call_credentials, compression, wait_for_ready, timeout, metadata)
 
+    @staticmethod
+    def Ping(request,
+            target,
+            options=(),
+            channel_credentials=None,
+            call_credentials=None,
+            insecure=False,
+            compression=None,
+            wait_for_ready=None,
+            timeout=None,
+            metadata=None):
+        return grpc.experimental.unary_unary(request, target, '/flwr.proto.Fleet/Ping',
+            flwr_dot_proto_dot_fleet__pb2.PingRequest.SerializeToString,
+            flwr_dot_proto_dot_fleet__pb2.PingResponse.FromString,
+            options, channel_credentials,
+            insecure, call_credentials, compression, wait_for_ready, timeout, metadata)
+
     @staticmethod
     def PullTaskIns(request,
             target,
diff --git a/src/py/flwr/proto/fleet_pb2_grpc.pyi b/src/py/flwr/proto/fleet_pb2_grpc.pyi
index cfa83f737439..33ba9440793a 100644
--- a/src/py/flwr/proto/fleet_pb2_grpc.pyi
+++ b/src/py/flwr/proto/fleet_pb2_grpc.pyi
@@ -16,6 +16,10 @@ class FleetStub:
         flwr.proto.fleet_pb2.DeleteNodeRequest,
         flwr.proto.fleet_pb2.DeleteNodeResponse]
 
+    Ping: grpc.UnaryUnaryMultiCallable[
+        flwr.proto.fleet_pb2.PingRequest,
+        flwr.proto.fleet_pb2.PingResponse]
+
     PullTaskIns: grpc.UnaryUnaryMultiCallable[
         flwr.proto.fleet_pb2.PullTaskInsRequest,
         flwr.proto.fleet_pb2.PullTaskInsResponse]
@@ -46,6 +50,12 @@ class FleetServicer(metaclass=abc.ABCMeta):
         context: grpc.ServicerContext,
     ) -> flwr.proto.fleet_pb2.DeleteNodeResponse: ...
 
+    @abc.abstractmethod
+    def Ping(self,
+        request: flwr.proto.fleet_pb2.PingRequest,
+        context: grpc.ServicerContext,
+    ) -> flwr.proto.fleet_pb2.PingResponse: ...
+
     @abc.abstractmethod
     def PullTaskIns(self,
         request: flwr.proto.fleet_pb2.PullTaskInsRequest,
diff --git a/src/py/flwr/proto/task_pb2.py b/src/py/flwr/proto/task_pb2.py
index 4d5f863e88dd..abf7d72d7174 100644
--- a/src/py/flwr/proto/task_pb2.py
+++ b/src/py/flwr/proto/task_pb2.py
@@ -18,7 +18,7 @@
 from flwr.proto import error_pb2 as flwr_dot_proto_dot_error__pb2
 
 
-DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x15\x66lwr/proto/task.proto\x12\nflwr.proto\x1a\x15\x66lwr/proto/node.proto\x1a\x1a\x66lwr/proto/recordset.proto\x1a\x1a\x66lwr/proto/transport.proto\x1a\x16\x66lwr/proto/error.proto\"\xf6\x01\n\x04Task\x12\"\n\x08producer\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\x12\"\n\x08\x63onsumer\x18\x02 \x01(\x0b\x32\x10.flwr.proto.Node\x12\x12\n\ncreated_at\x18\x03 \x01(\t\x12\x14\n\x0c\x64\x65livered_at\x18\x04 \x01(\t\x12\x0b\n\x03ttl\x18\x05 \x01(\t\x12\x10\n\x08\x61ncestry\x18\x06 \x03(\t\x12\x11\n\ttask_type\x18\x07 \x01(\t\x12(\n\trecordset\x18\x08 \x01(\x0b\x32\x15.flwr.proto.RecordSet\x12 \n\x05\x65rror\x18\t \x01(\x0b\x32\x11.flwr.proto.Error\"\\\n\x07TaskIns\x12\x0f\n\x07task_id\x18\x01 \x01(\t\x12\x10\n\x08group_id\x18\x02 \x01(\t\x12\x0e\n\x06run_id\x18\x03 \x01(\x12\x12\x1e\n\x04task\x18\x04 \x01(\x0b\x32\x10.flwr.proto.Task\"\\\n\x07TaskRes\x12\x0f\n\x07task_id\x18\x01 \x01(\t\x12\x10\n\x08group_id\x18\x02 \x01(\t\x12\x0e\n\x06run_id\x18\x03 \x01(\x12\x12\x1e\n\x04task\x18\x04 \x01(\x0b\x32\x10.flwr.proto.Taskb\x06proto3')
+DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x15\x66lwr/proto/task.proto\x12\nflwr.proto\x1a\x15\x66lwr/proto/node.proto\x1a\x1a\x66lwr/proto/recordset.proto\x1a\x1a\x66lwr/proto/transport.proto\x1a\x16\x66lwr/proto/error.proto\"\xf6\x01\n\x04Task\x12\"\n\x08producer\x18\x01 \x01(\x0b\x32\x10.flwr.proto.Node\x12\"\n\x08\x63onsumer\x18\x02 \x01(\x0b\x32\x10.flwr.proto.Node\x12\x12\n\ncreated_at\x18\x03 \x01(\t\x12\x14\n\x0c\x64\x65livered_at\x18\x04 \x01(\t\x12\x0b\n\x03ttl\x18\x05 \x01(\x01\x12\x10\n\x08\x61ncestry\x18\x06 \x03(\t\x12\x11\n\ttask_type\x18\x07 \x01(\t\x12(\n\trecordset\x18\x08 \x01(\x0b\x32\x15.flwr.proto.RecordSet\x12 \n\x05\x65rror\x18\t \x01(\x0b\x32\x11.flwr.proto.Error\"\\\n\x07TaskIns\x12\x0f\n\x07task_id\x18\x01 \x01(\t\x12\x10\n\x08group_id\x18\x02 \x01(\t\x12\x0e\n\x06run_id\x18\x03 \x01(\x12\x12\x1e\n\x04task\x18\x04 \x01(\x0b\x32\x10.flwr.proto.Task\"\\\n\x07TaskRes\x12\x0f\n\x07task_id\x18\x01 \x01(\t\x12\x10\n\x08group_id\x18\x02 \x01(\t\x12\x0e\n\x06run_id\x18\x03 \x01(\x12\x12\x1e\n\x04task\x18\x04 \x01(\x0b\x32\x10.flwr.proto.Taskb\x06proto3')
 
 _globals = globals()
 _builder.BuildMessageAndEnumDescriptors(DESCRIPTOR, _globals)
diff --git a/src/py/flwr/proto/task_pb2.pyi b/src/py/flwr/proto/task_pb2.pyi
index b9c10139cfb3..735400eca701 100644
--- a/src/py/flwr/proto/task_pb2.pyi
+++ b/src/py/flwr/proto/task_pb2.pyi
@@ -31,7 +31,7 @@ class Task(google.protobuf.message.Message):
     def consumer(self) -> flwr.proto.node_pb2.Node: ...
     created_at: typing.Text
     delivered_at: typing.Text
-    ttl: typing.Text
+    ttl: builtins.float
     @property
     def ancestry(self) -> google.protobuf.internal.containers.RepeatedScalarFieldContainer[typing.Text]: ...
     task_type: typing.Text
@@ -45,7 +45,7 @@ class Task(google.protobuf.message.Message):
         consumer: typing.Optional[flwr.proto.node_pb2.Node] = ...,
         created_at: typing.Text = ...,
         delivered_at: typing.Text = ...,
-        ttl: typing.Text = ...,
+        ttl: builtins.float = ...,
         ancestry: typing.Optional[typing.Iterable[typing.Text]] = ...,
         task_type: typing.Text = ...,
         recordset: typing.Optional[flwr.proto.recordset_pb2.RecordSet] = ...,
diff --git a/src/py/flwr/server/compat/driver_client_proxy.py b/src/py/flwr/server/compat/driver_client_proxy.py
index 1e6a84cbb42d..d666525c36ab 100644
--- a/src/py/flwr/server/compat/driver_client_proxy.py
+++ b/src/py/flwr/server/compat/driver_client_proxy.py
@@ -19,7 +19,7 @@
 from typing import List, Optional
 
 from flwr import common
-from flwr.common import MessageType, MessageTypeLegacy, RecordSet
+from flwr.common import DEFAULT_TTL, MessageType, MessageTypeLegacy, RecordSet
 from flwr.common import recordset_compat as compat
 from flwr.common import serde
 from flwr.proto import driver_pb2, node_pb2, task_pb2  # pylint: disable=E0611
@@ -129,6 +129,7 @@ def _send_receive_recordset(
                 ),
                 task_type=task_type,
                 recordset=serde.recordset_to_proto(recordset),
+                ttl=DEFAULT_TTL,
             ),
         )
         push_task_ins_req = driver_pb2.PushTaskInsRequest(  # pylint: disable=E1101
diff --git a/src/py/flwr/server/driver/driver.py b/src/py/flwr/server/driver/driver.py
index 0098e0ce97c2..afebd90ea265 100644
--- a/src/py/flwr/server/driver/driver.py
+++ b/src/py/flwr/server/driver/driver.py
@@ -18,7 +18,7 @@
 import time
 from typing import Iterable, List, Optional, Tuple
 
-from flwr.common import Message, Metadata, RecordSet
+from flwr.common import DEFAULT_TTL, Message, Metadata, RecordSet
 from flwr.common.serde import message_from_taskres, message_to_taskins
 from flwr.proto.driver_pb2 import (  # pylint: disable=E0611
     CreateRunRequest,
@@ -81,6 +81,7 @@ def _check_message(self, message: Message) -> None:
             and message.metadata.src_node_id == self.node.node_id
             and message.metadata.message_id == ""
             and message.metadata.reply_to_message == ""
+            and message.metadata.ttl > 0
         ):
             raise ValueError(f"Invalid message: {message}")
 
@@ -90,7 +91,7 @@ def create_message(  # pylint: disable=too-many-arguments
         message_type: str,
         dst_node_id: int,
         group_id: str,
-        ttl: str,
+        ttl: float = DEFAULT_TTL,
     ) -> Message:
         """Create a new message with specified parameters.
 
@@ -110,10 +111,10 @@ def create_message(  # pylint: disable=too-many-arguments
         group_id : str
             The ID of the group to which this message is associated. In some settings,
             this is used as the FL round.
-        ttl : str
+        ttl : float (default: common.DEFAULT_TTL)
             Time-to-live for the round trip of this message, i.e., the time from sending
-            this message to receiving a reply. It specifies the duration for which the
-            message and its potential reply are considered valid.
+            this message to receiving a reply. It specifies in seconds the duration for
+            which the message and its potential reply are considered valid.
 
         Returns
         -------
diff --git a/src/py/flwr/server/driver/driver_test.py b/src/py/flwr/server/driver/driver_test.py
index 5136f4f90210..3f1cd552250f 100644
--- a/src/py/flwr/server/driver/driver_test.py
+++ b/src/py/flwr/server/driver/driver_test.py
@@ -19,7 +19,7 @@
 import unittest
 from unittest.mock import Mock, patch
 
-from flwr.common import RecordSet
+from flwr.common import DEFAULT_TTL, RecordSet
 from flwr.common.message import Error
 from flwr.common.serde import error_to_proto, recordset_to_proto
 from flwr.proto.driver_pb2 import (  # pylint: disable=E0611
@@ -99,7 +99,8 @@ def test_push_messages_valid(self) -> None:
         mock_response = Mock(task_ids=["id1", "id2"])
         self.mock_grpc_driver.push_task_ins.return_value = mock_response
         msgs = [
-            self.driver.create_message(RecordSet(), "", 0, "", "") for _ in range(2)
+            self.driver.create_message(RecordSet(), "", 0, "", DEFAULT_TTL)
+            for _ in range(2)
         ]
 
         # Execute
@@ -121,7 +122,8 @@ def test_push_messages_invalid(self) -> None:
         mock_response = Mock(task_ids=["id1", "id2"])
         self.mock_grpc_driver.push_task_ins.return_value = mock_response
         msgs = [
-            self.driver.create_message(RecordSet(), "", 0, "", "") for _ in range(2)
+            self.driver.create_message(RecordSet(), "", 0, "", DEFAULT_TTL)
+            for _ in range(2)
         ]
         # Use invalid run_id
         msgs[1].metadata._run_id += 1  # pylint: disable=protected-access
@@ -170,7 +172,7 @@ def test_send_and_receive_messages_complete(self) -> None:
             task_res_list=[TaskRes(task=Task(ancestry=["id1"], error=error_proto))]
         )
         self.mock_grpc_driver.pull_task_res.return_value = mock_response
-        msgs = [self.driver.create_message(RecordSet(), "", 0, "", "")]
+        msgs = [self.driver.create_message(RecordSet(), "", 0, "", DEFAULT_TTL)]
 
         # Execute
         ret_msgs = list(self.driver.send_and_receive(msgs))
@@ -187,7 +189,7 @@ def test_send_and_receive_messages_timeout(self) -> None:
         self.mock_grpc_driver.push_task_ins.return_value = mock_response
         mock_response = Mock(task_res_list=[])
         self.mock_grpc_driver.pull_task_res.return_value = mock_response
-        msgs = [self.driver.create_message(RecordSet(), "", 0, "", "")]
+        msgs = [self.driver.create_message(RecordSet(), "", 0, "", DEFAULT_TTL)]
 
         # Execute
         with patch("time.sleep", side_effect=lambda t: sleep_fn(t * 0.01)):
diff --git a/src/py/flwr/server/superlink/fleet/grpc_rere/fleet_servicer.py b/src/py/flwr/server/superlink/fleet/grpc_rere/fleet_servicer.py
index 278474477379..eb8dd800ea37 100644
--- a/src/py/flwr/server/superlink/fleet/grpc_rere/fleet_servicer.py
+++ b/src/py/flwr/server/superlink/fleet/grpc_rere/fleet_servicer.py
@@ -15,7 +15,7 @@
 """Fleet API gRPC request-response servicer."""
 
 
-from logging import INFO
+from logging import DEBUG, INFO
 
 import grpc
 
@@ -26,6 +26,8 @@
     CreateNodeResponse,
     DeleteNodeRequest,
     DeleteNodeResponse,
+    PingRequest,
+    PingResponse,
     PullTaskInsRequest,
     PullTaskInsResponse,
     PushTaskResRequest,
@@ -61,6 +63,14 @@ def DeleteNode(
             state=self.state_factory.state(),
         )
 
+    def Ping(self, request: PingRequest, context: grpc.ServicerContext) -> PingResponse:
+        """."""
+        log(DEBUG, "FleetServicer.Ping")
+        return message_handler.ping(
+            request=request,
+            state=self.state_factory.state(),
+        )
+
     def PullTaskIns(
         self, request: PullTaskInsRequest, context: grpc.ServicerContext
     ) -> PullTaskInsResponse:
diff --git a/src/py/flwr/server/superlink/fleet/message_handler/message_handler.py b/src/py/flwr/server/superlink/fleet/message_handler/message_handler.py
index c99a7854d53a..2e696dde78e1 100644
--- a/src/py/flwr/server/superlink/fleet/message_handler/message_handler.py
+++ b/src/py/flwr/server/superlink/fleet/message_handler/message_handler.py
@@ -23,6 +23,8 @@
     CreateNodeResponse,
     DeleteNodeRequest,
     DeleteNodeResponse,
+    PingRequest,
+    PingResponse,
     PullTaskInsRequest,
     PullTaskInsResponse,
     PushTaskResRequest,
@@ -55,6 +57,14 @@ def delete_node(request: DeleteNodeRequest, state: State) -> DeleteNodeResponse:
     return DeleteNodeResponse()
 
 
+def ping(
+    request: PingRequest,  # pylint: disable=unused-argument
+    state: State,  # pylint: disable=unused-argument
+) -> PingResponse:
+    """."""
+    return PingResponse(success=True)
+
+
 def pull_task_ins(request: PullTaskInsRequest, state: State) -> PullTaskInsResponse:
     """Pull TaskIns handler."""
     # Get node_id if client node is not anonymous
diff --git a/src/py/flwr/server/superlink/fleet/vce/backend/raybackend_test.py b/src/py/flwr/server/superlink/fleet/vce/backend/raybackend_test.py
index 2610307bb749..dcac0b81d666 100644
--- a/src/py/flwr/server/superlink/fleet/vce/backend/raybackend_test.py
+++ b/src/py/flwr/server/superlink/fleet/vce/backend/raybackend_test.py
@@ -25,6 +25,7 @@
 from flwr.client import Client, NumPyClient
 from flwr.client.client_app import ClientApp, LoadClientAppError
 from flwr.common import (
+    DEFAULT_TTL,
     Config,
     ConfigsRecord,
     Context,
@@ -111,7 +112,7 @@ def _create_message_and_context() -> Tuple[Message, Context, float]:
             src_node_id=0,
             dst_node_id=0,
             reply_to_message="",
-            ttl="",
+            ttl=DEFAULT_TTL,
             message_type=MessageTypeLegacy.GET_PROPERTIES,
         ),
     )
diff --git a/src/py/flwr/server/superlink/fleet/vce/vce_api_test.py b/src/py/flwr/server/superlink/fleet/vce/vce_api_test.py
index 8c37399ae295..2c917c3eed27 100644
--- a/src/py/flwr/server/superlink/fleet/vce/vce_api_test.py
+++ b/src/py/flwr/server/superlink/fleet/vce/vce_api_test.py
@@ -26,7 +26,13 @@
 from unittest import IsolatedAsyncioTestCase
 from uuid import UUID
 
-from flwr.common import GetPropertiesIns, Message, MessageTypeLegacy, Metadata
+from flwr.common import (
+    DEFAULT_TTL,
+    GetPropertiesIns,
+    Message,
+    MessageTypeLegacy,
+    Metadata,
+)
 from flwr.common.recordset_compat import getpropertiesins_to_recordset
 from flwr.common.serde import message_from_taskres, message_to_taskins
 from flwr.server.superlink.fleet.vce.vce_api import (
@@ -97,7 +103,7 @@ def register_messages_into_state(
                 src_node_id=0,
                 dst_node_id=dst_node_id,  # indicate destination node
                 reply_to_message="",
-                ttl="",
+                ttl=DEFAULT_TTL,
                 message_type=(
                     "a bad message"
                     if erroneous_message
diff --git a/src/py/flwr/server/superlink/state/in_memory_state.py b/src/py/flwr/server/superlink/state/in_memory_state.py
index ac1ab158e254..7bff8ab4befc 100644
--- a/src/py/flwr/server/superlink/state/in_memory_state.py
+++ b/src/py/flwr/server/superlink/state/in_memory_state.py
@@ -17,7 +17,7 @@
 
 import os
 import threading
-from datetime import datetime, timedelta
+from datetime import datetime
 from logging import ERROR
 from typing import Dict, List, Optional, Set
 from uuid import UUID, uuid4
@@ -50,15 +50,13 @@ def store_task_ins(self, task_ins: TaskIns) -> Optional[UUID]:
             log(ERROR, "`run_id` is invalid")
             return None
 
-        # Create task_id, created_at and ttl
+        # Create task_id and created_at
         task_id = uuid4()
         created_at: datetime = now()
-        ttl: datetime = created_at + timedelta(hours=24)
 
         # Store TaskIns
         task_ins.task_id = str(task_id)
         task_ins.task.created_at = created_at.isoformat()
-        task_ins.task.ttl = ttl.isoformat()
         with self.lock:
             self.task_ins_store[task_id] = task_ins
 
@@ -113,15 +111,13 @@ def store_task_res(self, task_res: TaskRes) -> Optional[UUID]:
             log(ERROR, "`run_id` is invalid")
             return None
 
-        # Create task_id, created_at and ttl
+        # Create task_id and created_at
         task_id = uuid4()
         created_at: datetime = now()
-        ttl: datetime = created_at + timedelta(hours=24)
 
         # Store TaskRes
         task_res.task_id = str(task_id)
         task_res.task.created_at = created_at.isoformat()
-        task_res.task.ttl = ttl.isoformat()
         with self.lock:
             self.task_res_store[task_id] = task_res
 
diff --git a/src/py/flwr/server/superlink/state/sqlite_state.py b/src/py/flwr/server/superlink/state/sqlite_state.py
index 224c16cdf013..25d138f94203 100644
--- a/src/py/flwr/server/superlink/state/sqlite_state.py
+++ b/src/py/flwr/server/superlink/state/sqlite_state.py
@@ -18,7 +18,7 @@
 import os
 import re
 import sqlite3
-from datetime import datetime, timedelta
+from datetime import datetime
 from logging import DEBUG, ERROR
 from typing import Any, Dict, List, Optional, Set, Tuple, Union, cast
 from uuid import UUID, uuid4
@@ -54,7 +54,7 @@
     consumer_node_id        INTEGER,
     created_at              TEXT,
     delivered_at            TEXT,
-    ttl                     TEXT,
+    ttl                     REAL,
     ancestry                TEXT,
     task_type               TEXT,
     recordset               BLOB,
@@ -74,7 +74,7 @@
     consumer_node_id        INTEGER,
     created_at              TEXT,
     delivered_at            TEXT,
-    ttl                     TEXT,
+    ttl                     REAL,
     ancestry                TEXT,
     task_type               TEXT,
     recordset               BLOB,
@@ -185,15 +185,13 @@ def store_task_ins(self, task_ins: TaskIns) -> Optional[UUID]:
             log(ERROR, errors)
             return None
 
-        # Create task_id, created_at and ttl
+        # Create task_id and created_at
         task_id = uuid4()
         created_at: datetime = now()
-        ttl: datetime = created_at + timedelta(hours=24)
 
         # Store TaskIns
         task_ins.task_id = str(task_id)
         task_ins.task.created_at = created_at.isoformat()
-        task_ins.task.ttl = ttl.isoformat()
         data = (task_ins_to_dict(task_ins),)
         columns = ", ".join([f":{key}" for key in data[0]])
         query = f"INSERT INTO task_ins VALUES({columns});"
@@ -320,15 +318,13 @@ def store_task_res(self, task_res: TaskRes) -> Optional[UUID]:
             log(ERROR, errors)
             return None
 
-        # Create task_id, created_at and ttl
+        # Create task_id and created_at
         task_id = uuid4()
         created_at: datetime = now()
-        ttl: datetime = created_at + timedelta(hours=24)
 
         # Store TaskIns
         task_res.task_id = str(task_id)
         task_res.task.created_at = created_at.isoformat()
-        task_res.task.ttl = ttl.isoformat()
         data = (task_res_to_dict(task_res),)
         columns = ", ".join([f":{key}" for key in data[0]])
         query = f"INSERT INTO task_res VALUES({columns});"
diff --git a/src/py/flwr/server/superlink/state/state_test.py b/src/py/flwr/server/superlink/state/state_test.py
index d0470a7ce7f7..01ac64de1380 100644
--- a/src/py/flwr/server/superlink/state/state_test.py
+++ b/src/py/flwr/server/superlink/state/state_test.py
@@ -22,6 +22,7 @@
 from typing import List
 from uuid import uuid4
 
+from flwr.common import DEFAULT_TTL
 from flwr.proto.node_pb2 import Node  # pylint: disable=E0611
 from flwr.proto.recordset_pb2 import RecordSet  # pylint: disable=E0611
 from flwr.proto.task_pb2 import Task, TaskIns, TaskRes  # pylint: disable=E0611
@@ -73,7 +74,6 @@ def test_store_task_ins_one(self) -> None:
 
         assert task_ins.task.created_at == ""  # pylint: disable=no-member
         assert task_ins.task.delivered_at == ""  # pylint: disable=no-member
-        assert task_ins.task.ttl == ""  # pylint: disable=no-member
 
         # Execute
         state.store_task_ins(task_ins=task_ins)
@@ -91,7 +91,6 @@ def test_store_task_ins_one(self) -> None:
 
         assert actual_task.created_at != ""
         assert actual_task.delivered_at != ""
-        assert actual_task.ttl != ""
 
         assert datetime.fromisoformat(actual_task.created_at) > datetime(
             2020, 1, 1, tzinfo=timezone.utc
@@ -99,9 +98,7 @@ def test_store_task_ins_one(self) -> None:
         assert datetime.fromisoformat(actual_task.delivered_at) > datetime(
             2020, 1, 1, tzinfo=timezone.utc
         )
-        assert datetime.fromisoformat(actual_task.ttl) > datetime(
-            2020, 1, 1, tzinfo=timezone.utc
-        )
+        assert actual_task.ttl > 0
 
     def test_store_and_delete_tasks(self) -> None:
         """Test delete_tasks."""
@@ -420,6 +417,7 @@ def create_task_ins(
             consumer=consumer,
             task_type="mock",
             recordset=RecordSet(parameters={}, metrics={}, configs={}),
+            ttl=DEFAULT_TTL,
         ),
     )
     return task
@@ -442,6 +440,7 @@ def create_task_res(
             ancestry=ancestry,
             task_type="mock",
             recordset=RecordSet(parameters={}, metrics={}, configs={}),
+            ttl=DEFAULT_TTL,
         ),
     )
     return task_res
diff --git a/src/py/flwr/server/utils/validator.py b/src/py/flwr/server/utils/validator.py
index 846217b085a1..285807d8d0e7 100644
--- a/src/py/flwr/server/utils/validator.py
+++ b/src/py/flwr/server/utils/validator.py
@@ -36,8 +36,8 @@ def validate_task_ins_or_res(tasks_ins_res: Union[TaskIns, TaskRes]) -> List[str
         validation_errors.append("`created_at` must be an empty str")
     if tasks_ins_res.task.delivered_at != "":
         validation_errors.append("`delivered_at` must be an empty str")
-    if tasks_ins_res.task.ttl != "":
-        validation_errors.append("`ttl` must be an empty str")
+    if tasks_ins_res.task.ttl <= 0:
+        validation_errors.append("`ttl` must be higher than zero")
 
     # TaskIns specific
     if isinstance(tasks_ins_res, TaskIns):
diff --git a/src/py/flwr/server/utils/validator_test.py b/src/py/flwr/server/utils/validator_test.py
index 8e0849508020..926103c6b09a 100644
--- a/src/py/flwr/server/utils/validator_test.py
+++ b/src/py/flwr/server/utils/validator_test.py
@@ -18,6 +18,7 @@
 import unittest
 from typing import List, Tuple
 
+from flwr.common import DEFAULT_TTL
 from flwr.proto.node_pb2 import Node  # pylint: disable=E0611
 from flwr.proto.recordset_pb2 import RecordSet  # pylint: disable=E0611
 from flwr.proto.task_pb2 import Task, TaskIns, TaskRes  # pylint: disable=E0611
@@ -96,6 +97,7 @@ def create_task_ins(
             consumer=consumer,
             task_type="mock",
             recordset=RecordSet(parameters={}, metrics={}, configs={}),
+            ttl=DEFAULT_TTL,
         ),
     )
     return task
@@ -117,6 +119,7 @@ def create_task_res(
             ancestry=ancestry,
             task_type="mock",
             recordset=RecordSet(parameters={}, metrics={}, configs={}),
+            ttl=DEFAULT_TTL,
         ),
     )
     return task_res
diff --git a/src/py/flwr/server/workflow/default_workflows.py b/src/py/flwr/server/workflow/default_workflows.py
index 876ae56dcadc..42b1151f9835 100644
--- a/src/py/flwr/server/workflow/default_workflows.py
+++ b/src/py/flwr/server/workflow/default_workflows.py
@@ -21,7 +21,7 @@
 from typing import Optional, cast
 
 import flwr.common.recordset_compat as compat
-from flwr.common import ConfigsRecord, Context, GetParametersIns, log
+from flwr.common import DEFAULT_TTL, ConfigsRecord, Context, GetParametersIns, log
 from flwr.common.constant import MessageType, MessageTypeLegacy
 
 from ..compat.app_utils import start_update_client_manager_thread
@@ -127,7 +127,7 @@ def default_init_params_workflow(driver: Driver, context: Context) -> None:
                     message_type=MessageTypeLegacy.GET_PARAMETERS,
                     dst_node_id=random_client.node_id,
                     group_id="0",
-                    ttl="",
+                    ttl=DEFAULT_TTL,
                 )
             ]
         )
@@ -226,7 +226,7 @@ def default_fit_workflow(  # pylint: disable=R0914
             message_type=MessageType.TRAIN,
             dst_node_id=proxy.node_id,
             group_id=str(current_round),
-            ttl="",
+            ttl=DEFAULT_TTL,
         )
         for proxy, fitins in client_instructions
     ]
@@ -306,7 +306,7 @@ def default_evaluate_workflow(driver: Driver, context: Context) -> None:
             message_type=MessageType.EVALUATE,
             dst_node_id=proxy.node_id,
             group_id=str(current_round),
-            ttl="",
+            ttl=DEFAULT_TTL,
         )
         for proxy, evalins in client_instructions
     ]
diff --git a/src/py/flwr/server/workflow/secure_aggregation/secaggplus_workflow.py b/src/py/flwr/server/workflow/secure_aggregation/secaggplus_workflow.py
index 42ee9c15f1cd..326947b653ff 100644
--- a/src/py/flwr/server/workflow/secure_aggregation/secaggplus_workflow.py
+++ b/src/py/flwr/server/workflow/secure_aggregation/secaggplus_workflow.py
@@ -22,6 +22,7 @@
 
 import flwr.common.recordset_compat as compat
 from flwr.common import (
+    DEFAULT_TTL,
     ConfigsRecord,
     Context,
     FitRes,
@@ -373,7 +374,7 @@ def make(nid: int) -> Message:
                 message_type=MessageType.TRAIN,
                 dst_node_id=nid,
                 group_id=str(cfg[WorkflowKey.CURRENT_ROUND]),
-                ttl="",
+                ttl=DEFAULT_TTL,
             )
 
         log(
@@ -421,7 +422,7 @@ def make(nid: int) -> Message:
                 message_type=MessageType.TRAIN,
                 dst_node_id=nid,
                 group_id=str(cfg[WorkflowKey.CURRENT_ROUND]),
-                ttl="",
+                ttl=DEFAULT_TTL,
             )
 
         # Broadcast public keys to clients and receive secret key shares
@@ -492,7 +493,7 @@ def make(nid: int) -> Message:
                 message_type=MessageType.TRAIN,
                 dst_node_id=nid,
                 group_id=str(cfg[WorkflowKey.CURRENT_ROUND]),
-                ttl="",
+                ttl=DEFAULT_TTL,
             )
 
         log(
@@ -563,7 +564,7 @@ def make(nid: int) -> Message:
                 message_type=MessageType.TRAIN,
                 dst_node_id=nid,
                 group_id=str(current_round),
-                ttl="",
+                ttl=DEFAULT_TTL,
             )
 
         log(
diff --git a/src/py/flwr/simulation/ray_transport/ray_client_proxy.py b/src/py/flwr/simulation/ray_transport/ray_client_proxy.py
index c3493163ac52..5e344eb087ee 100644
--- a/src/py/flwr/simulation/ray_transport/ray_client_proxy.py
+++ b/src/py/flwr/simulation/ray_transport/ray_client_proxy.py
@@ -23,7 +23,7 @@
 from flwr.client import ClientFn
 from flwr.client.client_app import ClientApp
 from flwr.client.node_state import NodeState
-from flwr.common import Message, Metadata, RecordSet
+from flwr.common import DEFAULT_TTL, Message, Metadata, RecordSet
 from flwr.common.constant import MessageType, MessageTypeLegacy
 from flwr.common.logger import log
 from flwr.common.recordset_compat import (
@@ -105,7 +105,7 @@ def _wrap_recordset_in_message(
                 src_node_id=0,
                 dst_node_id=int(self.cid),
                 reply_to_message="",
-                ttl=str(timeout) if timeout else "",
+                ttl=timeout if timeout else DEFAULT_TTL,
                 message_type=message_type,
                 partition_id=int(self.cid),
             ),
diff --git a/src/py/flwr/simulation/ray_transport/ray_client_proxy_test.py b/src/py/flwr/simulation/ray_transport/ray_client_proxy_test.py
index 22c5425cd9fd..9680b3846f1d 100644
--- a/src/py/flwr/simulation/ray_transport/ray_client_proxy_test.py
+++ b/src/py/flwr/simulation/ray_transport/ray_client_proxy_test.py
@@ -24,6 +24,7 @@
 from flwr.client import Client, NumPyClient
 from flwr.client.client_app import ClientApp
 from flwr.common import (
+    DEFAULT_TTL,
     Config,
     ConfigsRecord,
     Context,
@@ -202,7 +203,7 @@ def _load_app() -> ClientApp:
                 src_node_id=0,
                 dst_node_id=12345,
                 reply_to_message="",
-                ttl="",
+                ttl=DEFAULT_TTL,
                 message_type=MessageTypeLegacy.GET_PROPERTIES,
                 partition_id=int(cid),
             ),