DNS issue

VirtualForce

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I hope someone can help me with this.

The company I work for is made up of 4 groups, each using thier own domain at hetzner. With 3 I have no problem whatsoever, people can get and sent mail 99% of the time.

However, the one company regularly gets timeouts for both sending and receiving.

I've done the most obvious and pinged both the pop and smtp server. Sometimes the prompt will sit there for a couple of seconds and then tell me it couldnt find the server and other times immediately tell me no reply was found. I mean immediately as in I've barely lifted my finger from the enter button and I get a responce back saying it couldnt find the host.

I then do a "ipconfig /flushdns" and this helps about half the time. If I look at the DNS cache the details under the smtp details for the company is empty. I guess that is way I get such a quick no server responce.

This is in Selby JHB but in Vereeniging when I ask a colleague to ping the server they get a possitive responce. I've also phoned Hetzner and they say all is well.

This happens on Windows XP, Win svr 2003 /2008

I think the DNS might somehow be the problem, we use the DNS configured by MWeb, can I use another DNS? If so, which ones do you guys use?

Our ISP is MWeb.

Thank you!
 
when it gives no response could you do a
nslookup yourmailserver.yourdomain.co.za 8.8.8.8
and
nslookup yourmailserver.yourdomain.co.za yourprimarydnsIP

I tend to use 8.8.8.8 and 8.8.4.4 ( Google's public DNS IP addresses ) at any site where external DNS resolution is problematic
 
Last edited:
might also be one too many (expired) mail exchanger records that's causing mail to time-out.
records with high priority (low numbers) might not exist anymore or simply time-out.

check MX records for the domain
also check using different DNS servers to see if your registrar is propagating DNS correctly.

goto command prompt

nslookup
set type=MX
domain.name

you'll get something like:

C:\Users\Administrator>nslookup
Default Server: UnKnown
Address: 192.168.1.254

> set type=MX
> google.com
Server: UnKnown
Address: 192.168.1.254

Non-authoritative answer:
google.com MX preference = 50, mail exchanger = alt4.aspmx.l.google.com
google.com MX preference = 30, mail exchanger = alt2.aspmx.l.google.com
google.com MX preference = 20, mail exchanger = alt1.aspmx.l.google.com
google.com MX preference = 40, mail exchanger = alt3.aspmx.l.google.com
google.com MX preference = 10, mail exchanger = aspmx.l.google.com

alt2.aspmx.l.google.com internet address = 74.125.43.26
alt1.aspmx.l.google.com internet address = 74.125.39.27
alt3.aspmx.l.google.com internet address = 209.85.173.26
aspmx.l.google.com internet address = 209.85.229.27
alt4.aspmx.l.google.com internet address = 74.125.127.26
>



The above reports that google.com has 5 mail server addresses.
1 primary and 4 fail-over (with different priorities)

assign the same priority to 2 or more servers and you get load balancing by round-robin.
 
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