I have a peculiar situation. We get a lot of traffic on our
server..almost 2-3 people every second. We are getting the remote IP
address using remote_addr function but, donot get the remote host
using remote_host. It still just gives the IP address. How do i find
out the remote host name?. I am fearing if I implement a reverse look
up on my server, it will go down due to excess load as every iP will
need to be checked in the DNS for the host name. any suggestions on
how this can be done?

Amit

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Request for Question Clarification by joseleon-ga on 02 Oct 2003 02:19 PDT

Hello, amazingclick:
  In which development language are you working, in PHP there is a
function that may help you:

<?php
  $ip='64.72.132.36';
  echo gethostbyaddr($ip);
?>

This returns:

Hosting-132-36.PHPWebHosting.com

Is this the information are you looking for?

Regards.

Hi, amazingclick-ga:

Most implementations of a "ping" client will have a reverse lookup
option, i.e. to resolve IP addresses to hostnames.  On my "windows"
platform this takes the form of command-line option "-a".  To use
joseleon-ga's example:

ping -a 64.72.132.36

returns the name Hosting-132-36.PHPWebHosting.Com (even though the
actual ping times out for me).

regards, mathtalk-ga

we have java running. Ping cannot be used as it will bring down the
server immediately when we make a lot of ping requests every moment.
Remote_Host function is not working. It just gets the IP, not the
addr.

Amit

Hi, amazingclick-ga:

I guess my question would be why it would be necessary to make these
requests "every moment".  In many applications the reverse lookup
would be deferred to a point in time when a human being is prepared to
look at the results.  For example, you might be logging the hits to
your Web site during a certain reporting period.  The report
generation process, in addition to summarizing the logs, could add in
any hostname references (say for the top 20 most active "users") that
might be available.

There is no guarantee that a particular IP address will resolve to a
hostname, nor is the mapping between hostnames and IP addresses always
constant over time.  It would help to provide additional advice if we
understood your purpose in trying to obtain the hostnames and what the
time constraints are.

regards, mathtalk-ga

Are you talking about an apache webserver?  If so, you can monitor
your apache logs using a log-analyzer tool (I like Faststats).  Most
such analyzers will do a reverse-dns lookup so you see hostnames not
IP addresses.

There is a product out on the market that does what you need quite
well. I have used it once and liked it. It is called "CountryHawk" by
CyScape ( http://www.cyscape.com ). I am not in any way associated
with them, fyi.