Retry DNS timeout more aggresively

[estensen]

DNS was down for me today (now more resilient with backup yay) and the logs says contacting DNS times out every 10 min. Not sure if it's working for a long time before logging, but to me I think it would be nice to be a bit more aggressive and try again a bit sooner that after 10 min.

WARN  | DNSResolver | I/O exception contacting remote DNS server when resolving all.mainnet.ethdisco.net
java.io.IOException: Timed out while trying to resolve all.mainnet.ethdisco.net./TXT, id=61644
	at org.xbill.DNS.Resolver.send(Resolver.java:170)
	at org.apache.tuweni.discovery.DNSResolver.resolveRecordRaw(DNSResolver.kt:155)
	at org.apache.tuweni.discovery.DNSResolver.resolveRecord(DNSResolver.kt:73)
	at org.apache.tuweni.discovery.DNSResolver.visitTree(DNSResolver.kt:120)
	at org.apache.tuweni.discovery.DNSResolver.visitTree(DNSResolver.kt:111)
	at org.apache.tuweni.discovery.DNSResolver.collectAll(DNSResolver.kt:95)
	at org.apache.tuweni.discovery.DNSTimerTask.run(DNSDaemon.kt:89)
	at java.base/java.util.TimerThread.mainLoop(Timer.java:566)
	at java.base/java.util.TimerThread.run(Timer.java:516)

[macfarla]

Hi @estensen thanks for your feedback - some thoughts -

• the DNS entries are updated from here https://github.com/ethereum/discv4-dns-lists on a daily basis so most of the time as long as you connect once to the DNS server you'll have the latest entries
• even if you can't connect to your DNS, you can still run discovery
• if everything is working fine, 10 minutes might be too frequent to update
• but if your DNS was down, 10 minutes seems like a long time

[Ayo91]

How did you solve it? I added new DNS servers to my network configuration and reboot the machine but the message is still shown...

[macfarla]

@ayo91 it is normal to get occasional errors like that - Besu tries to contact several DNS servers - but some DNS servers may be down, it's out of our control. As long as some are contactable, you should be fine.

[estensen]

Experienced this twice in the last week. Have set DNS to Cloudflare and Google as backup. Maybe network providers fault? Anyway, causing some downtime :/