query regarding reverse IP
Gareth Llewellyn
gareth.llewellyn at itvision.net
Fri May 11 08:44:31 UTC 2007
http://www.dnsstuff.com/ is your friend!
Generally reverse DNS is governed by your ISP. This quick extract from a
reverse DNS lookup should explain it:
Preparation:
The reverse DNS entry for an IP is found by reversing the IP, adding it
to "in-addr.arpa", and looking up the PTR record.
So, the reverse DNS entry for 67.19.87.202 is found by looking up the
PTR record for
202.87.19.67.in-addr.arpa.
All DNS requests start by asking the root servers, and they let us know
what to do next.
See How Reverse DNS Lookups Work for more information.
How I am searching:
Asking b.root-servers.net for 202.87.19.67.in-addr.arpa PTR record:
b.root-servers.net says to go to dill.arin.net. (zone:
67.in-addr.arpa.)
Asking dill.arin.net. for 202.87.19.67.in-addr.arpa PTR record:
dill.arin.net [192.35.51.32] says to go to NS1.THEPLANET.COM.
(zone: 19.67.in-addr.arpa.)
Asking NS1.THEPLANET.COM. for 202.87.19.67.in-addr.arpa PTR record:
Reports core.networksaremadeofstring.co.uk. [from 207.44.128.228]
Answer:
67.19.87.202 PTR record: core.networksaremadeofstring.co.uk. [TTL
86400s] [A=67.19.87.202]
Now when I am searching the other way it is YOUR DNS server that answers
the queries:
How I am searching:
Searching for core.networksaremadeofstring.co.uk A record at
h.root-servers.net [128.63.2.53]: Got referral to ns1.nic.uk. (zone:
uk.) [took 49 ms]
Searching for core.networksaremadeofstring.co.uk A record at ns1.nic.uk.
[195.66.240.130]: Got referral to ns2.networksaremadeofstring.co.uk.
(zone: networksaremadeofstring.co.uk.) [took 125 ms]
Searching for core.networksaremadeofstring.co.uk A record at
ns2.networksaremadeofstring.co.uk. [67.19.87.203]: Reports
core.networksaremadeofstring.co.uk. [took 44 ms]
Response:
Domain Type Class TTL Answer
core.networksaremadeofstring.co.uk. A IN 14400
67.19.87.202
networksaremadeofstring.co.uk. NS IN 14400
ns2.networksaremadeofstring.co.uk.
networksaremadeofstring.co.uk. NS IN 14400
ns1.networksaremadeofstring.co.uk.
ns1.networksaremadeofstring.co.uk. A IN 14400
67.19.87.202
ns2.networksaremadeofstring.co.uk. A IN 14400
67.19.87.203
-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of sylvan dacounha
Sent: 11 May 2007 09:37
To: General Red Hat Linux discussion list
Subject: query regarding reverse IP
Dear All,
I am new to DNS concepts.. and sorry for this silly query
i have a query regarding reverse IP and apprecite if someone could
help me...
I have a redhat 9 with bind bind-9.2.1-9
i have a DNS server running on xx.xx.xx.1 IP and this DNS server has
one domain example.com .
I also have a mailserver running on the same IP for the example.com
domain and is working fine . and also the ISP has the reverse IP setup
for the above domain that is abc.example.com
now i am also using the same DNS server to host another domain
example1.com and is workin fine.
I also have recently configured a mail server for the example1.com
domain and the mail server is running on another machine that is
xx.xx.xx.2
now i see that when i send mail to servers like hotmail n gmail the
mail goes to junk mail folder rather than to inbox but when i send mail
from my first domain that is example.com it goes fine
now when i do a reverse for my xx.xx.xx.1 IP it gives me example.com
but when i do a reverse for my xx.xx.xx.2 IP it cannot find the
example1.com domain.
now i want to know if the reverse lookup can be done locally in my DNS
or the ISP.
and if the ISP has to do it which IP for my example1.com domain i have
to give.
IS it xx.xx.xx.2 ????
also if i have a third domain configured on the same DNS server and a
mailserver running on 3rd machine whould i also give the 3rd IP of the
mail server to do a reverse to my ISP
appreciate ur help
thnks and regards
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