RR behavior

[PT T]

If an authoritative server is configured (and verified) to return a list of 
A records with fixed order:



1.1.1.1

2.2.2.2

3.3.3.3



All client (or “local” or “recursive” or whatever the correct term is) DNS 
servers will RR this list, regardless of TTL setting. However, if the same 
server returns only 2 records instead of 3 in the order:



1.1.1.1

2.2.2.2



I find that some DNS servers pass the list order through to the client stub 
resolver unchanged, while others re-order the list. The authoritative server 
is BIND, I assume the client DNS servers are various versions of BIND, but 
can’t be sure (I tried this on various providers, Adelphia, BellSouth, 
Charter, Cox, SBC, etc.).



Can someone shed light on why the behavior with 2 A records is different 
than with 3 on some servers? A variation in the RR algorithm between BIND 
versions maybe? Also (not considering SRV records) is there any way to 
influence this behavior from the authoritative server (e.g. prevent the RR 
from happening)?





Thanks,



Pete.

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