Devil Panther

How do I write my own DNS lookup to list all sub domains on a host.
Because you see i want to write an smtp server, but as i've learned, after i send mail with my smtp server, it sends mail to the destination's smtp server. but how my smtp server finds the destination's smtp server's address?
So I did a little reasearch and I found out that it's done with dns lookup, but i could not find a manual on how to do that.

Please help.
Thanks.

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"I don't suffer from insanity but enjoy every minute of it" - Edgar Allen Poe

http://www.Bloodware.net - Developing free software for the community.

anonytmouse

You need to lookup mx dns records. MX is short for Mail Exchange. These records point to the incoming smtp server for a domain.

Some operating systems have apis to lookup mx records. For example, DnsQuery is available on Windows 2000/XP. Alternatively you can use a library or just some code using sockets.

C code using sockets:
http://cvs.synchro.net/cgi-bin/viewc...bs3/mxlookup.c

DnsQuery function:
http://www.developer2.com/features/stories/34508.html

Devil Panther

Thanks alot.

__________________
"I don't suffer from insanity but enjoy every minute of it" - Edgar Allen Poe

http://www.Bloodware.net - Developing free software for the community.