Order of NS records given by bind

[Ricardo Oliveira]

Hi all,

Does anyone know what algorithm BIND uses to order the NS records in a  
DNS reply? e.g.

dig @66.6.49.217 NS yahoo.com
yahoo.com.		160275	IN	NS	ns6.yahoo.com.
yahoo.com.		160275	IN	NS	ns8.yahoo.com.
yahoo.com.		160275	IN	NS	ns1.yahoo.com.
yahoo.com.		160275	IN	NS	ns2.yahoo.com.
yahoo.com.		160275	IN	NS	ns3.yahoo.com.
yahoo.com.		160275	IN	NS	ns4.yahoo.com.
yahoo.com.		160275	IN	NS	ns5.yahoo.com.

Successive queries give different orderings of nameservers.  I though  
it was decreasing RTT order, but wanted to confirm.

Thanks,

--Ricardo