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Re: Telnet and Reverse Lookup



Hi Paul,

sorry for taking so long to get back to you....

I have seen this happen when you a single host name
point to two ip addresses: IE:

$ host omniture.112.2o7.net
omniture.112.2o7.net has address 216.52.17.213
omniture.112.2o7.net has address 216.52.17.116

If you telnet (port 80) directly to one of these addresses,
(ip address) you will instantly see a reply.

If however you telnet to

telnet omniture.112.2o7.net 80

You will see that it takes quite a while as the telnet CLIENT
attempts to do a reverse lookup....

Very strange....

Andrew



On Feb 12, 2006, at 12:37 AM, Paul Dwerryhouse wrote:

On Fri, Feb 10, 2006 at 11:31:47AM +0100, Andrew Miehs wrote:
Why does the telnet client do a reverse lookup when connecting to a
server?!

Client? I've just run a couple of tests with telnet, while watching the logs of my caching nameserver, and I do not see any indication that the
client is doing a reverse lookup.

Are you perhaps meaning that the remote server is performing a reverse
lookup when you connect to it? If that is the case, it is almost
certainly the tcp wrappers on the machine that is doing it.



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