Don't use a router as a DNS resolver for customers. Just don't. Frank
-----Original Message----- From: cisco-nsp [mailto:[email protected]] On Behalf Of Sascha E. Pollok Sent: Friday, August 15, 2014 5:56 AM To: [email protected] Subject: [c-nsp] Strange corrupt DNS Cache in IOS Hello networking fellows! We are trying to find the cause of a corrupt local DNS cache of a Cisco 1803 running 15.1(4)M8 (also appeared on 12.4something - 15.1 ist just a desperate attempt of solving). The router acts as a local DNS resolver for locally connected clients using "ip dns server". Every now and then it seems to break locally cached IPv4 A-RRs like this: Router#show hosts test.fqdn.fqdn None (temp, OK) 0 IP 0.0.0.5 <--- This seems to happen for hosts that also have an AAAA RR. To us it looks like it mixes AAAA and A records as the IPv6 address for this host is [...]::5. This happens with other hosts too. The host is sometimes first seen correctly with an "IP" and "IPv6" entry in the cache but then changes to the broken "IP" RR while sometimes even keeping the correct IPv6 entry. It never happens to the IPv6 address. Debugging "debugging domain" and "debugging domain replies" didnt give a clue. Thanks for any hints! Sascha _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
