Question on properly setting up a reverse on a IP address...

Rich Parkin RParkin at ldmi.com
Thu Apr 29 13:45:54 UTC 2004


>>> Barry Margolin <barmar at alum.mit.edu> 4/28/2004 5:11:45 PM >>>
In article <c6otcr$26q5$1 at sf1.isc.org>,
 Jason <jwilliams at courtesymortgage.com> wrote:

> Hello everyone.
> 
> Just wanted to clarify on the proper way to setup a reverse on a IP 
> address. Since this particular IP address is going to be attached to
my 
> mail server and a lot of people require a proper reverse set, just
want 
> to make sure that it is correct.
> 
> If my IP address is
> 
> 222.123.130.11
> 
> I should add something like:
> 
> 11.130.123.222.in-addr.arpa
> 
> That would be the correct method?
> 

Yes.  You also need to ensure that the reverse domain is delegated to 
your servers.

-- 
Barry Margolin, barmar at alum.mit.edu 
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

To elaborate a bit...

1.) The reverse domain must be delegated to your nameservers, either by
ARIN in the case of a block that's /24 or larger, or by your ISP in the
case of a block that's /25 or smaller.  If you're not the authority for
your IP block, you'll need your ISP's help with this.

2.) You need a zone configuration statement in your config file for the
in-addr.arpa zone pointing to a zone file.  If you own the whole /24
block, your zone would be "130.123.222.in-addr.arpa".

3.) You need a zone file for the reverse zone.  It will consist of an
SOA, NS records, and a bunch of PTR records similar to this:

11.130.123.222.in-addr.arpa.      IN PTR     
mymailserver.realname.tld.  ; substitute the real hostname of your mail
server here.
12.130.123.222.in-addr.arpa.      IN PTR      whatever.hostname.here.

(and so on)

Don't forget the trailing dot here.  An easier way to write it would
be:

@                                       ; this is shorthand for current
origin or "this zone"
11                     IN PTR       mymailserver.realname.tld.
12                     IN PTR       whatever.hostname.here.

Richard Parkin
System Administrator
CCNA
Data Center Operations
LDMI Telecommunications


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