DNS requests optimization

[AskAlexSharov]

It seems that some DNS requests are done every second:
erigontech/erigon#6876 (comment)

Is it possible to optimize it? Probably it's something related to announcement period?

[anacrolix]

Yes it is very likely due to announce failures, maybe some of those hosts aren't resolving, in which case it will occur once a minute until it does. One solution might be to wait for longer on DNS failure if that's the case. But also if you are running many simultaneous torrents like I suspect you are, the DNS lookups should be shared anyway. I also answered in erigontech/erigon#6876 (comment) by accident, everything there also applies.