DNS and reverse delegation


Configuration of Bind for reverse DNS PTR records classless

Once your ISP has configured reverse delegation you can see it with dig.


# dig +trace -x123.2.3.4

Near the end you will see a CNAME statement something like this:

??????????????????? CNAME 4.24/29.3.2.123.in-addr.arpa.

or this

??????????????????? CNAME 4.24.29.3.2.123.in-addr.arpa.

or

??????????????????? CNAME 4.0-5.3.2.123.in-addr.arpa.

The format of these CNAMEs are not standard and it appears one needs to create a separate zone for each IP address - bind does not seem to understand any of these besides the class specific ones such as:

3.2.123.in-addr.arpa.

So in your named.conf.local file your zone statement looks like this

zone "4.24/29.3.2.123.in-addr.arpa" IN {
 type master;
 file "/etc/bind/db.123.2.3.4";
};

In the zone file you need something like this:

$TTL 345600
@ IN SOA ns1.xtronics.com. hostmaster.xtronics.com. (
 2014032000  ; serial-date+2digit
 12000  ; refresh
 900  ; retry
 120000  ; expire
 3600)  ; minimum TTL
;
 NS ns1.example.com.
 NS ns2.example.com.
 PTR example.com.
 TXT "v=spf1  ip4:123.2.3.4 -all"
 SPF "v=spf1  ip4:123.2.3.4 -all"

Top Page wiki Index

Disclaimer

This information may have errors; It is not permissible to be read by anyone who has ever met a lawyer.
Use is confined to Engineers with more than 370 course hours of electronic engineering for theoretical studies.
ph +1(785) 841-3089

Email inform@xtronics.com

(C) Copyright 1994-2017, Transtronics, Inc. All rights reserved
TranstronicsĀ® is a registered trademark of Transtronics, Inc.
All trademarks are the property of their respective owners.