nanog mailing list archives

Re: Detecting a non-existent domain


From: Jack Bates <jbates () brightok net>
Date: Tue, 23 Sep 2003 16:37:57 -0500


Kee Hinckley wrote:


Getting practical for a minute. What is the optimal way now to see if a given host truly exists? Assume that I can't control the DNS server--I need to have this code run in any (*ix) environment. Assume also that I don't want to run around specialcasing specific IP addresses or TLDs--this needs to work reliably no matter what the domain. User gives me a string, and I need to see if the given host is a real machine.


A set comparison between the domain your interested in and *.TLD will inform you if the domain is pointed to the same IP addresses as the wildcard. In many cases, this is sufficient and can be made to work dynamically and quickly with most software and scripts.

-Jack


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