Hello, We had mail outage which was caused by one of our three recursive caching DNS servers to be answering a query like seen bellow.
What could explain the fact that this record had zero answers? and why would the cache server, apparently, cache this answer for over 10 hours (until I manually cleared the cache)? A user reported that the cache server was returning AAAA records, but no IPv4, though we dont have an example of such query/response saved. I guess the fact that the server had AAAA record would explain why the bellow response is a NOERROR? ➜ ~ dig imap.gmail.com @141.161.200.201 ; <<>> DiG 9.9.2-P1 <<>> imap.gmail.com @141.161.200.201 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34151 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 5 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;imap.gmail.com. IN A ;; AUTHORITY SECTION: gmail.com. 94747 IN NS ns3.google.com. gmail.com. 94747 IN NS ns2.google.com. gmail.com. 94747 IN NS ns4.google.com. gmail.com. 94747 IN NS ns1.google.com. ;; ADDITIONAL SECTION: ns2.google.com. 269064 IN A 216.239.34.10 ns1.google.com. 269064 IN A 216.239.32.10 ns3.google.com. 269064 IN A 216.239.36.10 ns4.google.com. 269064 IN A 216.239.38.10 ;; Query time: 56 msec ;; SERVER: 141.161.200.201#53(141.161.200.201) ;; WHEN: Sat Aug 24 16:21:17 2013 ;; MSG SIZE rcvd: 186 Thanks a lot, Mohamed.
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