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Old 10-07-2005, 04:32 AM   #1
pazvant
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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...?

Thx
 
Old 10-07-2005, 08:59 AM   #2
MensaWater
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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 131.81.141.55

Then you'd want to add the following PTR for it for reverse lookup:
131.81.141.55 IN PTR host1.domain.com

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, 05:03 AM   #3
pazvant
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Bind

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 1.1.1.1
# set type=PTR
# 2.2.22.2 => i got the answer 1.1.1.1 is my DNS server but.

when i choose another dns like

#server 2.2.2.2 => 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, 07:36 AM   #4
scowles
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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 (in-addr.arpa 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 1.1.1.1

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!
 
  


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