Running BIND9 that uses TCP

Ketil Froyn isc_bind at
Tue Apr 18 08:29:20 UTC 2006

Jason Mitchell wrote:

> Correct me if i'm wrong, but my understanding is that BIND uses UDP by 
> default, and retries with TCP is UDP fails or it receives a truncated 
> response.

DNS uses UDP by default, a server responding to TCP only will not be 
seen by normal resolvers. Resolvers only retry with TCP if a UDP 
response is received with the truncated bit set, not when UDP fails.

Ketil Froyn
ketil at

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