[CentOS] DNS and Reverse Adresses

Mon Jan 23 18:42:36 UTC 2012
Peter Eckel <lists at eckel-edv.de>

Hi Götz, 

> My question: dose maybe someone forgot the 192.168.200.x reverse zone
> files and config

probably. 

> and can I just create a file like that for the 172.17
> hosts and adding the config for the reverse zone to my named.conf?

Yes, *if* you either have the only DNS in your network (not a hierarchically lower level that gets its domains delegated from the next higher level) or the 200.168.192.in-addr.arpa domain has been delegated to you. Having the authority over the 'domainname.de' domain and hostnames that resolve to 192.168.200.x addresses does not automatically mean that you have authority over the said reverse lookup domain as well. 

You can check whether some other name server resolves 192.168.200.x addresses by entering 

  dig -x 192.168.200.x

If you get NXDOMAIN, there is probably either more mis-configuration around (happens frequently in my experience), or there actually is no other server that could provide reverse lookup. You can also try to check the delegation of the 200.168.192.in-addr.arpa address by issuing the command 

  dig 200.168.192.in-addr.arpa NS

The pointers you get in return (if any) should give you an indication whether you have authority to resolve reverse lookups for 192.168.200.x addresses.

Again, if yours is/are the only or main authoritative DNS server(s) in the (internal) network, these considerations do not apply.  

Viele Grüße, 

  Peter.