0000063: Default PTR Domain for "reverse dns zones"

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Severity

Reproducibility

Date Submitted

Last Update

0000063

[MyDNS-NG] Global

feature

N/A

2010-11-06 19:33

Reporter

wiese

View Status

public

Assigned To

Priority

normal

Resolution

open

Platform

Status

new

Projection

none

OS Version

ETA

none

Fixed in Version

Product Version

Target Version

Product Build

Summary

0000063: Default PTR Domain for "reverse dns zones"

Description

Hiya,

a very useful feature for almost all ISPs:
Default PTR Domain

Explanation:

You have 2 zones (SOA) created:

my-domain.com
0.168.192.in-addr.arpa

The SOAs have the following RRs:

my-domain.com:
@ IN NS ns1.my-provider.com.
@ IN NS ns2.my-provider.com.
@ IN A 123.123.123.123
www IN A 123.123.123.123
192-168-0-222.ip4 IN A 123.123.123.123

0.168.192.in-addr.arpa:
@ IN NS ns1.my-provider.com.
@ IN NS ns2.my-provider.com.
5 IN PTR my-ptr-host.domain.com.

Within the mydns.conf configuration exists one entry:
default-ptr-domain = my-domain.com

Scenario:
Someone asks your DNS for the PTR of: 123.64.168.192.in-addr.arpa
The DNS will refuse the query because no SOA exists in the data base.

Someone asks your DNS for the PTR of: 5.0.168.192.in-addr.arpa
The DNS will answer "my-ptr-host.domain.com" because SOA and RR found. Default behavior.

Now, someone asks your DNS for the PTR of: 22.0.168.192.in-addr.arpa
The DNS has the SOA for 0.168.192.in-addr.arpa but no RR for 22. If in mydns.conf is defined a "default-ptr-domain" value it will generate a response if the SOA exists but no PTR RR, within this scheme: 192-168-0-22.ip4.my-domain.com

Now, to have the reverse dns working right, the same has to be if someone asks the A RR for: 192-168-0-22.ip4.my-domain.com. The DNS will check if this domain has a SOA. If so, it will check if it has an RR. If SOA exists, but no RR and the SOA is defined as "default-ptr-domain" generate a answer to the IP.
So if someine requests 192-168-0-22.ip4.my-domain.com the generated answer will be 192.168.0.22.

If the RR exists in the data base, it has surely priority and the DNS server will return this one.

Like this, ISPs don't have to generate for all their IP's "standard PTR" entries in the database which saves work and size of the database. Especially for IPv6 this is important. Who wants to put 79.228.162.514.264.337.593.543.950.336 "default PTR records" in the arpa zone and the domain zone just because the LIR has a /32 allocation from the RIR.

I think it's a great feature for those who wants to have "standard PTR's" for their IPs, and almost everyone does this. With this feature you have to enter only used/real PTR's within the zones, which saves a lot of work and entries.

Cheers,
Sven

Steps To Reproduce

Additional Information

Issue History
Date Modified	Username	Field	Change
2010-11-06 19:33	wiese	New Issue

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