Cannot get ip address of mx record kienhwa.hk

[Chris Boot]

Alex Tang wrote:
> Hi All
>
> Sometimes my user cannot send email to kienhwa.hk. I find out that the dns server cannot get the ip address of the mx record at the same time.
>
>   
>> set q=mx
>> kienhwa.hk
>>     
> Server:         dns
> Address:        
>
> kienhwa.hk      mail exchanger = 10 kienhwa.hk.
>
> but I can get the ip address of the mx by enter the host name only
>
>   
>> set q=a
>> kienhwa.hk
>>     
> Server:         dns
> Address:        
>
> Name:   kienhwa.hk
> Address: 202.134.124.67
>
> also the ttl of the domain is 0
>
>   
>> set q=soa
>>     
>         origin = NS1.OGDNS.COM
>         mail addr = NS1.OGDNS.COM
>         serial = 1
>         refresh = 10800
>         retry = 3600
>         expire = 86400
>         minimum = 0
>
> What cause the problem ?
> My bind version is 8.3.7
>   

Looks to me like you have a TTL of 0, which completely prevents any sort
of caching of the record. This both adds load to your DNS server (since
every request has to lookup the record) and might have the effect that
the result of the lookup is removed from a cache before being used by a
mail server or other system. Even those free web-based dynamic DNS
systems have a TTL of 60 seconds...

Chris