I have two web servers at our colocation running CentOS 6.0. One runs our main marketing web site (production server) and the other is a staging server for the production server, so almost an exact replica. Both of them are behind a firewall and have private IP addresses. The firewall is connected to our main office with a site-to-site VPN tunnell. Both of the servers have their nameservers set up to use our internal DNS servers here in our main office.
On the production server, I'm facing this exact same issue, even the same hostname of phx1-ss-2-lb.cnet.com. The problem is that whenever I ping a domain name that doesn't exist, I get that cnet.com hostname in return. Even on my own domains, if I do somestupidsubdomain.mydomain.com, it returns with the cnet address. In that thread, they said it was NXDOMAIN hijacking and that they should use different name servers. In my situation, this production server is using the same nameservers as everyone else in the company, but this isn't an issue for anyone else. Even the staging server that's a mirror of the production server isn't having the issue.
I've checked the /etc/hosts file and nothing out of the ordinary is there. I looked up how to flush the local DNS cache through either nscd or bind and neither are even installed. I used nslookup and queried my two assigned DNS servers and they came back with domain not found errors, as would be expected.
Where should I look next?
I used tcpdump on port 53 and than pinged some jibberish domain and this is the output I got
14:55:39.884442 IP 192.168.4.11.59726 > 192.168.0.22.domain: 27749+ A? asdfjjjf.com. (30) 14:55:39.905778 IP 192.168.0.22.domain > 192.168.4.11.59726: 27749 NXDomain 0/1/0 (103) 14:55:39.905930 IP 192.168.4.11.46752 > 192.168.0.22.domain: 18476+ A? asdfjjjf.com.com. (34) 14:55:39.926982 IP 192.168.0.22.domain > 192.168.4.11.46752: 18476 2/0/0 CNAME phx1-ss-2-lb.cnet.com., A 188.8.131.52 (82)
14:55:39.962067 IP 192.168.4.11.44686 > 192.168.0.22.domain: 5275+ PTR? 184.108.40.206.in-addr.arpa. (44)
14:55:39.983324 IP 192.168.0.22.domain > 192.168.4.11.44686: 5275 1/0/0 PTR phx1-ss-2-lb.cnet.com. (79)
So if I'm reading this right, does that mean that my DNS server is definitely responding with the cnet.com address? If I use nslookup, set it to the 192.168.0.22 server, and query a jibberish domains A record, it returns with nothing.