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I'm using a slightly modified version of named 9.8 to manage an internal-only domain. The forward lookups are working ok but reverse isn't. There aren't any error messages - just no hostname returned.

What I've tried:

>dig hostname
- gives (what looks like) all relevant info
QUESTION, ANSWER, AUTHORITY, ADDITIONAL - all present and correct

taking the IP address from this -
>dig -x  <ip address>
QUESTION and AUTHORITY only returned. No hostname

>host <hostname>
hostname <hostname> has address <ip address>

>host -a <ip address>
Trying "<reversed IP>.in-addr.arpa"
Host <reversed IP>.in-addr.arpa. not found: 3(NXDOMAIN)
Received 100 bytes from <DNS server>#53 in 4 ms

So this says my DNS server isn't responding to reverse requests.. but is to forward requests? Is there some other way to debug my named.conf file?

NOTE: through all of this - no errors in /var/log/named.log or /var/log/messages.

System is running RHEL 5 (x64)

EDIT: note that dig -x <IP address not in my zone> works fine.

All dig commands are against the primary (and only) nameserver.

snip from named.conf:

zone "20.10.in-addr.arpa" {
   type master;
   database "mysqldb named_pocl 10_20 localhost named_acct password";
   allow-query { trusted-nets; };
   allow-update { trusted-nets; };
   allow-transfer { trusted-nets; };
   notify no;
   forwarders { };
};

I'm assuming that this named extension isn't returning the correct values for the reverse lookup. What I'm hoping to learn is how to determine what is missing or erroneous so I can fix it.

There are two tables with information for BIND: 'pocl' (domain name - contains 'A' records) and '10_20' (ip range - contains 'PTR' records). Each table contains an entry for every server + entries for 'NS', 'SOA', 'MX', etc.

** Looking through the source for the db connector I'm not convinced that it even supports PTR records. This might be a huge, gaping reason why it isn't working. Yikes.

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  • Are you querying the authoritative nameserver directly? Does it have the reverse zone that would contain the name you are trying to look up? You may want to show the config + zone data. Apr 15, 2014 at 17:48
  • Response to the edit: To reiterate, is there a zone that would contain the name you are trying to look up? If the IP network is eg 10.1.2.0/24, is there an 2.1.10.in-addr.arpa zone? If so, what does it contain? Apr 15, 2014 at 18:10
  • There is a relevant entry in the named.conf file - however it calls out to a record in a database instead of a zone file. I'm including it to show details.
    – ethrbunny
    Apr 15, 2014 at 18:15
  • Ok, so MySQL BIND SDB Driver is what you are running? Is that correct? What data does the table contain? Apr 15, 2014 at 18:29
  • 1
    If the problem is specific to the SDB thing, which I am actually familiar with, you may also want to look at BIND DLZ if you specifically want BIND with data in a mysql db. (Otherwise PowerDNS is also an option for database-backed nameserver software.) Apr 15, 2014 at 18:45

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