Bind - OPT UDPsize=1232 ?

[Karl Pielorz]

Hi,

If I switch between having Bind go lookup a name, and dig - I can see a 
difference in tcpdump, i.e.

Bind 9.16.16:

11:44:19.041785 IP (tos 0x0, ttl 64, id 3613, offset 0, flags [none], proto 
UDP (17), length 66)
    Us.54445 > Them.53: 3636 [1au] MX? somedomain.org. ar: . OPT 
UDPsize=1232 DO (38)

So, Bind is uses 'OPT UDPsize=1232 DO (38)'

Whereas, dig on the same host generates:

11:48:19.294690 IP (tos 0x0, ttl 64, id 28121, offset 0, flags [none], 
proto UDP (17), length 78)
    Us.30953 > Them.53: 19570+ [1au] MX? somedomain.org. ar: . OPT 
UDPsize=4096 (50)

Dig uses 'OPT UDPsize=4096 (50)'


Anyone know why the Bind query appears to set such a low UDPsize? - We've 
nothing in our config setting sizes, or maximums.


Thanks,

-Karl