Reverse Lookup Zones Question

  • Thread starter Thread starter Donald P. Crawford
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Donald P. Crawford

Hi ya!

Is it possible to set up a reverse lookup zone in the DNS
server to resolve addresses to any and all queries? How
can my server do a reverse lookup for addresses that
exsist out in the real world that are not part of my
class or address range? For example, how is a reverse
lookup done for say, www.cnn.com or www.microsoft.com?
Can I refer the queries to other DNS servers, like DNS
forwarding?

Thanks!

(e-mail address removed)
 
In
Donald P. Crawford said:
Hi ya!

Is it possible to set up a reverse lookup zone in the DNS
server to resolve addresses to any and all queries? How
can my server do a reverse lookup for addresses that
exsist out in the real world that are not part of my
class or address range? For example, how is a reverse
lookup done for say, www.cnn.com or www.microsoft.com?
Can I refer the queries to other DNS servers, like DNS
forwarding?

Thanks!

(e-mail address removed)
Click to expand...

Unknown IP queries are forwarded just like name queries.
The only time they won't forward is when the local DNS thinks it is
authoritative for the IP address. Such as maybe a mis-configured reverse
lookup zone. The most common of this is creating a reverse lookup zone for
your internal IP of 192.168.x.x but you create the zone as 192.in-addr.arpa.
While this will work for your internal addresses it conflicts with public
addresses and reverse queries will fail to these addresses.
This is typically unimportant unless you have a local SMTP server, set to
reject mail from mail server without a PTR record.
 
Hi ya!

Is it possible to set up a reverse lookup zone in the DNS
server to resolve addresses to any and all queries? How
can my server do a reverse lookup for addresses that
exsist out in the real world that are not part of my
class or address range? For example, how is a reverse
lookup done for say, www.cnn.com or www.microsoft.com?
Can I refer the queries to other DNS servers, like DNS
forwarding?

Thanks!

(e-mail address removed)
Click to expand...
******************** REPLY SEPARATER *********************
Reverse lookup is not quite the same as a forward lookup. The root servers are
queried for who has authority for a particular network. Sometimes the root
servers will provide information for networks lower than "A" class, but for the
sake of argument, lets assume that they supply just "A" class (xxx.)
information. Armed with the information, the authoratative server is queried
for the owner of the "B" class network (xxx.xxx), and that server is in turn
queried for the "C" class network (xxx.xxx.xxx), which supplies the answer. Sub
networks of "C" class networks can be given authority as well, but that is a
more complicated process.

Because it is a top down process, what you do on your own DNS server is only
relavent to your own network. In order for users outside of your network to get
the correct reverse lookup information, that authority must be passed down to
you from the authoratative supplier above you.

J.A. Coutts
Systems Engineer
MantaNet/TravPro
 
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