Reverse mapping DNS update

Sivakumar Thiyagarajan sivakumar_id at yahoo.com
Fri Dec 8 21:43:49 UTC 2000



>
>No offense, but I think you need to do some more
reading on how DNS 
>works.

None taken and you bet I need hell a lot more reading
to do. Thanks for your response. 

But was I way off in expecting the reverse mapping 
update to automatically take place, given that I was
able to do the hostname-address mapping update. 

I am looking ito the RFC and also some books to
decipher them. Can you point me towards any nice
websites/books on nsupdate stuff? -  the general 
DNS stuff does not seem to discuss this.

thanks
p.s.
sorry to use your personal(?) id. I lost my thread's
header when I switched to the digest mode of the mail
list.

>Reverse (address-to-name) mappings in DNS are stored
in a completely
>different part of the namespace hierarchy than
forward 
>(name-to-address)
>mappings. If you want <ipaddress> to reverse-resolve
to <hostname>, 
>this requires a totally separate and distinct record
than the one which 
enables
><hostname> to forward-resolve to <ipaddress>.
Specifically, for address
>a.b.c.d, you'd need to add a record of type PTR with
the name
>d.c.b.a.in-addr.arpa. If you are not authoritative
for the appropriate
>reverse domain (e.g. c.b.a.in-addr.arpa,
b.a.in-addr.arpa or 
>a.in-addr.arpa)
>then in general you cannot create an address-to-name
mapping for your 
>host.
>Note, however, that if you have a smaller-than-256
range of addresses 
>(let's
>say, the lower half of a.b.c.*), then with the
co-operation of the 
>owner of
>the parent reverse domain (e.g. the owner of
c.b.a.in-addr.arpa), you can
>play some aliasing or delegation tricks to allow you
effectively 
>control
>those reverse mappings. See RFC 2317 for more details
and/or search the
>archives of this list for some permutation of
"classless in-addr.arpa
>delegation".
>- Kevin
>
>Sivakumar Thiyagarajan wrote:
>
>> hi gurus,
>>
>> After using nsupdate to add a host and its ip
address, given the hostname
>> nslookup is able to get ip address when but not the
other way around.
>> i.e. given the ip address, the nslookup doesnt give
the host name back.
>>
>> #  nsupdate
>> > update add <hostname> <ttl> IN A < ipaddress >
>> >
>> Any thing else needs to be done? The host name
appears in a DNS database
>> dump though.
>>



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