bind-8.1.2, lost MX's

[torben fjerdingstad]

Sometimes mail fails, apparently because bind-8.1.2 gives
wrong information about MX's.

Our mail server is a precedence, say, 20 MX for some customers
who have their own mail server as precedence 10.

Sometimes, mail bounces because bind either says
our mail server has the highest precedence, or
there are no MX's for the domain name.

It is hard to prove. Here is what I have (2 cases):

1) This error was on my mail server, mail.net.uni-c.dk, which is
using ns.darenet.dk for the resolver (bind-8.1.2):

qmail error report:
<ca at dfu.min.dk>:
Sorry. Although I'm listed as a best-preference MX or A for that host,
it isn't in my control/locals file, so I don't treat it as local. (#5.4.6)

In the above case, I am NOT the best preference MX, so bind must
have delivered bogus data. The truth is:
dfu.min.dk      preference = 15, mail exchanger = hfi02.dfu.min.dk
dfu.min.dk      preference = 25, mail exchanger = mail.net.uni-c.dk

Next,
Using nslookup, it happens that a MX is not found. Here,
the MX is missing in the first nslookup, while it is present in
the second lookup. What is going on here?

# nslookup -type=any daisy.dk
Name Server:  ns.darenet.dk
Address:  130.226.1.2

Non-authoritative answer:
daisy.dk        nameserver = www.daisy.dk
daisy.dk        nameserver = dns100.telia.com
daisy.dk
        origin = www.daisy.dk                                               
        mail addr = Administrator.daisy.dk                                  
        serial = 12                                                         
        refresh = 3600 (1 hour)                                            
        retry   = 600 (10 mins)                                             
        expire  = 86400 (1 day)                                             
        minimum ttl = 3600 (1 hour)                                         

Authoritative answers can be found from:                                    
daisy.dk        nameserver = www.daisy.dk                                   
daisy.dk        nameserver = dns100.telia.com                               
www.daisy.dk    internet address = 194.255.48.4                            
dns100.telia.com        internet address = 194.19.152.2                     

A moment later:

# nslookup -type=any daisy.dk                              
Name Server:  ns.darenet.dk                                                 
Address:  130.226.1.2                                                       

Non-authoritative answer:                                                   
daisy.dk        nameserver = www.daisy.dk                                  
daisy.dk        nameserver = dns100.telia.com                               
daisy.dk                                                                    
        origin = www.daisy.dk                                               
        mail addr = Administrator.daisy.dk                                  
        serial = 12                                                         
        refresh = 3600 (1 hour)                                             
        retry   = 600 (10 mins)                                             
        expire  = 86400 (1 day)                                            
        minimum ttl = 3600 (1 hour)                                         
daisy.dk        preference = 5, mail exchanger = mail.daisy.dk              

Authoritative answers can be found from:                                    
daisy.dk        nameserver = www.daisy.dk                                   
daisy.dk        nameserver = dns100.telia.com                               
www.daisy.dk    internet address = 194.255.48.4                            
dns100.telia.com        internet address = 194.19.152.2                     
mail.daisy.dk   internet address = 194.255.48.10                            

-- 
Med venlig hilsen / Regards 
Netdriftgruppen / Network Management Group
UNI-C          

Tlf./Phone   +45 35 87 89 41        Mail:  UNI-C                                
Fax.         +45 35 87 89 90               Bygning 304
E-mail: torben.fjerdingstad at uni-c.dk       DK-2800 Lyngby