Finding MX Records

[Matthew Thompson]

I've come across something that to an extent has stumped me.

I've written a DNS query client in VB (Please no comments about the choice
of language) which takes an email address and attempts to determine wether
the destination is deliverable. IT performs an query to our local DNS server
and then it either returns a positive (if it receives MX entries) or queries
the NS records it receives back.

This looks to have worked pretty well so far but a small number of the
failed addresses would appear to have no MX records associated.

One example is thmc.com.tw

My software queries our local DNS server and gets back the following (as
nslookup displays it)

Server:  [10.1.1.245]
Address:  10.1.1.245

thmc.com.tw
        origin = thmcsrv.thmc.com.tw
        mail addr = administrator.thmc.com.tw
        serial = 24
        refresh = 3600 (1 hour)
        retry   = 600 (10 mins)
        expire  = 86400 (1 day)
        minimum ttl = 3600 (1 hour)

10.1.1.245 is the internal nic on the DNS server - it is connected to the
Internet properly.

If I perform the query on thmcsrv.thmc.com.tw I get _exactly_ the same back
from that server as well.

So I'm leaft wondering 1. are the addresses valid and 2 how do I know if
they are.

Any assistance greatly appreciated.

M at t :o)

--  
Matthew Thompson - Fairplay Publications Limited - www.fairplay.co.uk
matthewt at fairplay.co.uk - tel: +44 20 8645 2800 - fax: +44 20 8660 2824
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