bryancall commented on issue #8761: URL: https://github.com/apache/trafficserver/issues/8761#issuecomment-4827449988
Looking at the current DNS code, the single query ATS sends to a nameserver during the failover period is the deliberate recovery probe, not a client lookup. Real client lookups skip servers marked down: in write_dns (src/iocore/dns/DNS.cc) the round-robin loop rounds past any ns_down entry and bails out if the selected server is down. The only traffic that reaches a down server during the failover period is the periodic recovery probe issued from mainEvent (retry_named and try_primary_named, sent at most once per primary-retry interval). That probe is how ATS learns when a downed nameserver has come back online, so it is intended behavior, and removing it would leave a recovered server permanently marked down. Since real queries are not routed to a down server and the probe is by design, I am closing this. If you are seeing actual client lookups (not the recovery probe) hitting a down server, please reopen with a reproduction and the proxy.config.dns settings in use. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
