Host command timing out sporadically

[Lyle Giese]

On 05/02/12 12:12, Paul Marais wrote:
> Hi,
> I'm having an issue where my postfix server is having trouble with some lookups.
> When I type 'host<hostname>', 80% of the time I get decent reply speed, but for 20% I get a 5 second delay, or even a timeout.
>
> My nameserver is configured to only allow recursion for hosts on my local network, and I have my ISP dns in my forwarders.
> My resolv.conf has 127.0.0.1, my internal ip, and the ip for my isp DNS
>
> Any help will be greatly appreciated.
>
> Thanks
> Paul
>
>
Don't use host.  It's not telling us what is going wrong and it's only 
doing an A record lookup of host name.

Postfix does an MX lookup for the domain and then an A record lookup for 
the mail server(s) in the MX records.

Learn to use dig.

Do this:

dig mx example.com

If the answer is mail.example.com do this:

dig mx example.com

if either fail do this:

dig +trace mx example.com
or
dig +trace mail.example.com

And see if you can catch the failure and then we can do more for you.  
The other side of this may be that your Internet connection is 
overloaded and you are dropping packets or it's taking too long for the 
query to get out and get the response.

Lyle Giese
LCR Computer Services, Inc.