udp vs tcp query

[Benny Pedersen]

On Sun, 23 Oct 2011 13:56:21 +1000, Noel Butler wrote:
> I think you have something broken, bind uses UDP by default, if
> it can not connect to a dns server on UDP it then retries on TCP.
>
>  It also uses TCP for AXFR's

correct, its not my problem how axfr works, as i have sleeped on it 
now, got the idear its might be edns0 problem relatted ?, thats explain 
why i see some dnsbl domains works and others not working

how do i test this ?

imho edns0 will always use tcp not udp, correct ?