Allowable reverse mapping zone file names

/dev/rob0 rob0 at
Sat Aug 27 19:23:19 UTC 2016

On Sat, Aug 27, 2016 at 10:47:36AM -0500, Tom Browder wrote:
> I do not control 3-octet networks but need reverse mapping for my 
> mail server.

Discuss that with your ISP or netblock owner.

> Two questions:
> 1. Where is the doc that completely describes the allowable reverse 
> mapping zone file names?

There is no limit within BIND on what you name a zone file.  I 
suspect you might be wondering about the names of 
*zones* instead?

To use an example,, a resolver would request a PTR record 
named "".  That is the reversed octets of the 
dotted-quad IPv4 address with "" appended.

A zone could exist at any of these names:

(See also RFC 2317 for "classless" reverse DNS delegation, but no,
DO NOT read that: I only mention it for completeness, as we have 
pedantic posters on this list ... myself included. ;) )

> 2. When running my own authoritative name servers, do I need 
> reverse mapping for anything other than my single mail server?

You only need an zone IF that zone has been delegated to 
your nameserver[s] by a netblock owner or by your RIR (such as RIPE 
for Europe, ARIN for North America, et c.)

If the zone has not been delegated to you, ^^ go back to the top and 
talk to your ISP or netblock owner.

If you're still confused, tell us what your IP address is and we 
might be able to tell you who to contact.
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