TYPE MX Resolution Problem Windows NT 4.0

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Balbino Brito - 18 Jul 2003 16:02 GMT

Hello Everyone.

I'm having an strange issue here.

Scenario:
Windows NT 4.0 SP 6.0a
MS Proxy 2.0 SP1
Dual NIC
Nic 01: Private IP
Nic 02: Public IP
DNS Servers: My ISP DNS Servers IP's
RRAS

Everything was working just fine. Now, I installed a Mail Server Behind the
Proxy, and so far it was working fine. But today I realized that there are
SOME domains that ALWAYS get bounced Emails with an MX Resolution Temporary
Error.

So I went to my proxy server and tried to resolve the domains from there.

I ran the command NSLOOKUP and I set the TYPE=MX

I tried to resolve the domains and it returned the following error:

***myispDNSservername can't find bandalux.es: Server Failed (bandalux.es is
one of the domains that fail resolution)

Now, i talked to my ISP and HE CAN resolve that MX name, but I CAN'T.

So i've been looking everywhere for a solution, and honestly at this point
I'm completely out of ideas. I restarted the Proxy Server, and apparently
there's no ipconfig /registerdns or ipconfig/flushdns to somehow refresh
those tables, if there's any table at all.

I really need help on this....

Thanks in advance

Balbino Brito

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Brendon Rogers - 18 Jul 2003 19:20 GMT

when you run NSLOOKUP it uses your PC's DNS server to query. You can set
NSLOOKUP to use another DNS server. Also, sometimes it takes 5 or 6 attempts
for a valid response, so don't try the lookup once.

Try the following (you will query UUnet's DNS server):

NSLOOKUP
server 198.6.1.2
set type=mx
bandalux.es

Now, when I did that its not returning the name of an MX server:

> bandalux.es

Server: cache01.ns.uu.net
Address: 198.6.1.2

DNS request timed out.
timeout was 2 seconds.
bandalux.es
primary name server = dns1.rsmicro.es
responsible mail addr = admin.dns1.rsmicro.es
serial = 2002103118
refresh = 10800 (3 hours)
retry = 3600 (1 hour)
expire = 604800 (7 days)
default TTL = 86400 (1 day)

So lets set NSLOOKUP to query the primary nameserver for the bandalux.es
domain:

server dns1.rsmicro.es
Default Server: dns1.rsmicro.es
Address: 213.229.186.81

Querying again for bandalux.es returns no MX host. So I would suggest the
problem lies with their DNS setup.

> set type=mx
> bandalux.es

Server: dns1.rsmicro.es
Address: 213.229.186.81

bandalux.es
primary name server = dns1.rsmicro.es
responsible mail addr = admin.dns1.rsmicro.es
serial = 2002103118
refresh = 10800 (3 hours)
retry = 3600 (1 hour)
expire = 604800 (7 days)
default TTL = 86400 (1 day)

> Hello Everyone.
>
[quoted text clipped - 35 lines]
>
> Balbino Brito

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Balbino Brito - 18 Jul 2003 23:55 GMT

Hello Brendon

I did the test as you suggested and you are right....

The server returned :

No mail exchange (MX) records available for bandalux.es

I hate the ISP Technician... He told me that he got an answer and that CAN?T
be true at all if bandalux doesn?t have an MX record.

I did the same test with euler.ciens.ucv.ve (another domain with the same
situation) and the same result came out from the server

Thanks a lot for your help Brendon, you?ve been a great eyeopener

Balbino.

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Thor Kottelin - 19 Jul 2003 09:51 GMT

> No mail exchange (MX) records available for bandalux.es

I agree. I'd just like to add that with the current setup, mail for
bandalux.es would go to 213.9.216.2, since the A record points to that
address (implicit MX rule).

Thor

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