Reverse DNS query - PTR records ..

Posted on 2008-10-04
Medium Priority
Last Modified: 2013-12-16
My linux box has two interfaces eth0 and eth1  configured with and respectively .

But as soon as the box is restarted , the box send reverse dns query (PTR ) to  nameserver defined in /etc/resolv.conf file .
 1. why this reverse dns query is sent out ? Can i assign any name to these interfaces so that it wont query a PTR records .

i defined entries in /etc/hosts file  for eth0 and eth1 , and defined /etc/host.conf . But still it sends out reverse dns query .

2 . Why it is not picking entries from /etc/hosts file .
3 . There is a reverse dns query for also . WHy it is so ?
Question by:91Change
  • 3

Author Comment

ID: 22640349
but if i add  
nameserver   then everything seems to work fine .How this is possible since   no dns server running on my linux box . But if i make changes in /etc/hosts file , it takes reboot to take effect .

Can you help with these problems ?
LVL 51

Assisted Solution

by:Keith Alabaster
Keith Alabaster earned 200 total points
ID: 22640400
You have a network defined as by the nature of having a nic with the ip address of - why would you NOT expect the server to try and contact the nameserver listed as responsible for the network to check that there is a ptr record for


Author Comment

ID: 22640848
There is no PTR for my address in nameserver . I dont have admin privilege in nameserver .

These dns reverse queries keep coming and really slowing down my connection . I can see it thru wireshark . So i need to resolve in my box itself by some means .

Author Comment

ID: 22640895
My reverse dns query  get resolved  in the box itself ? .....I would like to do this happen ..
LVL 41

Accepted Solution

noci earned 300 total points
ID: 22673745
Reverse queries are mostly done because some software was asked to log a hostname into the logfiles. THen any address involved on your system will have it's name asked out.

You can't prevent them otherwise as NOT to log hostnames. (in whatever software is asked to do that).

Also if you have access restrictions in xinetd or others and have a name there the incoming address is looked up and compared to check for access.

If you don't want to use DNS, than you need to setup host files.
But configuring the named server to have PTR zones is not that difficult
so why not take that easy route.

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