I have essentially the same problem on a Redhat 6.2 server and a 7.1 server. It took me a while to notice, and I can't pinpoint anything I changed that seems relevant. The problem is: reverse DNS on my static IP addresses doesn't work through my local DNS servers. It *does* work throughout the rest of the net, so far as I can tell (I've got an outside account, and it even works when I simply point my local tools at an outside server), and I *can* do reverse lookup on *other* IP addresses; just not my own. Each of the servers is dual-homed (on one NIC); gw.dd-b.net is 63.224.10.74 and 10.0.0.205. ns2.dd-b.net is 63.224.10.73 and 10.0.0.200. Here are some real examples, run on the 6.2 system: gw:Mail> host gw.dd-b.net gw.dd-b.net has address 63.224.10.74 gw.dd-b.net mail is handled (pri=12849) by ns2.dd-b.net gw.dd-b.net mail is handled (pri=12833) by mail.dd-b.net That's my main server. gw:Mail> host 63.224.10.74 Host not found. I can't do reverse lookup on it locally (resolv.conf says 127.0.0.1, then 10.0.0.200). gw:Mail> host 63.224.10.74 ns3.qwest.net Using domain server: Name: ns3.qwest.net Address: 63.226.138.15 Aliases: 74.10.224.63.IN-ADDR.ARPA domain name pointer gw.dd-b.net Reverse lookup works fine through an outside server, though. gw:Mail> host 216.239.37.100 100.37.239.216.IN-ADDR.ARPA domain name pointer www.google.com I can do reverse DNS on *other* addresses just fine! (which is why it took a while to notice this problem). gw:Mail> host visi.com visi.com has address 209.98.98.8 visi.com mail is handled (pri=20) by denv.mx.visi.com visi.com mail is handled (pri=10) by mta.mc.mpls.visi.com gw:Mail> host 209.98.98.8 8.98.98.209.IN-ADDR.ARPA domain name pointer isis.visi.com Another working reverse lookup. Things are similar on the 7.1 server. Note that 6.2 is bind 8 and 7.1 is bind 9. gw is primary DNS for a few dozen domains, ns2 is secondary DNS for most of them. This is obviously some configuration glitch of mine, but I can't figure it out. I've thrashed around and tried a bunch of things, but haven't learned anything useful that I can see yet. Help! Oh, hosts.txt looks like this (essentially the same on both systems except for swapping a couple of addresses): 127.0.0.1 localhost localhost.localdomain 63.224.10.78 nat nat.dd-b.net 10.0.0.200 ns2 ns2.dd-b.net 10.0.0.205 gw ns gw.dd-b.net 10.0.0.0 INSIDE # Network 63.224.10.72 OUTSIDE # Network -- David Dyer-Bennet / Welcome to the future! / dd-b at dd-b.net Photos: http://dd-b.lighthunters.net/ Book log: http://www.dd-b.net/dd-b/Ouroboros/booknotes/