Cannot get ip address of mx record kienhwa.hk

[Chris Buxton]

First, if you can avoid it, don't use nslookup. It's misleading and  
silly. Use dig instead - if you want dig for windows, download the  
BIND for Windows binary package. (If you don't want to use the  
installer, just drag the executable to a handy location. You'll also  
need a library; when you try to run it, it will tell you which  
library is missing.)

In this case, the two name servers for kienhwa.hk have different  
copies of the zone. The name servers appear to be load balancers,  
rather than something full-featured like BIND. fpdns.pl can't  
identify them, at least not from my location.

The relevant records are as follows:

kienhwa.hk.             0       IN      MX      10 kienhwa.hk.
kienhwa.hk.             0       IN      A       202.134.124.67
kienhwa.hk.             0       IN      A       202.134.124.67

Each name server reports a different A record, and neither puts the A  
record in the Additional section of the response. This, along with  
the 0 TTL's, may be what's tripping up your BIND server - it gets the  
MX record, looks up the A record, and then no longer has the MX  
record. Or something like that. I know very old versions of BIND had  
trouble with 0 TTL's, but I know that was at least largely fixed a  
long time ago.

BIND 9 should have no trouble with this, though. So the solution is  
probably going to be to upgrade BIND. This may not be a trivial  
undertaking, depending on your situation, but it's pretty important  
for a variety of reasons. BIND 8 should no longer be used for most  
purposes.

Chris Buxton
Men & Mice

On Aug 7, 2006, at 9:49 PM, 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
>
> Help Help
>
> Thx
>
>
>