Visit Jeremy's Blog.
Go Back > Forums > Linux Forums > Linux - Networking
User Name
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.


  Search this Thread
Old 10-07-2005, 03:32 AM   #1
Registered: Jul 2003
Location: Istanbul
Distribution: slack
Posts: 43

Rep: Reputation: 15
DNS Reverse lookup problem

Hi guys,

My DNS server can make reverse mapping both on my local network and
outside when i select my dns server ip for query.However on an another
DNS server i can normally make quaries but reverse mapping quaries did
not give any answer ...

Do you have any idea why the other DNS servers give no reverse mapping
quaries, altough answering normal quaries...?

Old 10-07-2005, 07:59 AM   #2
LQ Guru
Registered: May 2005
Location: Atlanta Georgia USA
Distribution: Redhat (RHEL), CentOS, Fedora, CoreOS, Debian, FreeBSD, HP-UX, Solaris, SCO
Posts: 6,945
Blog Entries: 14

Rep: Reputation: 1163Reputation: 1163Reputation: 1163Reputation: 1163Reputation: 1163Reputation: 1163Reputation: 1163Reputation: 1163Reputation: 1163
Your zone file has to have BOTH an "A" record and a "PTR" record for each host. The PTR is what allows for the reverse look up.

Example say you have the following for forward lookup:
host1 IN A

Then you'd want to add the following PTR for it for reverse lookup: IN PTR

You put the domain in the PTR so that reverse lookups will give you fully qualified domain name (FQDN). For forward lookups its not necessary because the zone file will append the domain name to the host being queried for.
Old 10-10-2005, 04:03 AM   #3
Registered: Jul 2003
Location: Istanbul
Distribution: slack
Posts: 43

Original Poster
Rep: Reputation: 15

Hi , thankx for your reply however the problem is'nt PTR record syntax or something else familiar abuot
configuration, my dns server can reply reverse quaries only i choose my dns server for query like

# nslookup
# server
# set type=PTR
# => i got the answer is my DNS server but.

when i choose another dns like

#server => no other answer repliess ?? The problem is something familiar about ripe, maybe
we have to record our ip for PTR mappings...
Old 10-10-2005, 06:36 AM   #4
Registered: Sep 2004
Location: Texas, USA
Distribution: Fedora
Posts: 620

Rep: Reputation: 31
If I understand your post correctly... most DNS servers are configured to only answer queries for authoritative zones (domains) ONLY. All other queries would be rejected -or- simply return the root servers. I know thats how I have my DNS server configured. I don't want folks on the internet to specify my name server in their resolver lib configuation.

With regards to PTR records - these zones must be delegated to your name server by your ISP. Most ISP's refuse to delegate PTR zones ( zones) to your name server, but you may get lucky. FWIW" My ISP will NOT delegate PTR records.

A good command to see how your PTR record is delegated from the root servers is "dig". Something like:

dig +trace -x

would show all the name servers involved in retrieving the answer. i.e. recursion If your name server is not listed in the output, then you will most likely need to contact your ISP (or the last name server listed) and see if you can get them to delegate these PTR records to your name server.

Good luck!


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Fastest way in perl to reverse dns lookup Jon- Programming 7 07-20-2016 12:50 PM
Ident / Reverse DNS Lookup maq Linux - Networking 1 03-31-2005 05:59 PM
DNS reverse lookup problems... pdmackenzie Linux - Networking 2 09-19-2003 05:00 PM
Reverse DNS lookup, or any way to contact an IP.. MasterC Linux - Networking 6 02-21-2003 03:34 AM
reverse DNS lookup phil1076 Linux - General 1 01-22-2002 03:24 PM > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 10:00 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration