Mantis Bugtracker

Viewing Issue Advanced Details Jump to Notes ] View Simple ] Issue History ] Print ]
ID Category Severity Reproducibility Date Submitted Last Update
0000063 [MyDNS-NG] Global feature N/A 2010-11-06 19:33 2010-11-06 19:33
Reporter wiese View Status public  
Assigned To
Priority normal Resolution open Platform
Status new   OS
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
Tags No tags attached.
Attached Files

- Relationships

There are no notes attached to this issue.

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


Mantis 1.1.6[^]
Copyright © 2000 - 2008 Mantis Group
Powered by Mantis Bugtracker