Secondary DNS

[Barry Margolin]

In article <91t7aa$ocu at pub3.rc.vix.com>, Jon Bibeau <jbibeau at c-i-s.com> wrote:
>
>I have a simple question... When you create secondary DNS server (ie: set
>the zones on the secondary as a slave) what happens when the master dies and
>the TTL of the record expires? And then what happens when the secondary
>can't get to the master?

Slave servers don't care about TTL -- that's used only by caching servers.

Slave servers use the Expire time in the SOA record.  Until that time
expires, they will continue to respond to DNS queries for the domain.
After that, the specific behavior seems to depend on the version of BIND.
Until 8.2, BIND would continue to respond to queries, but it would answer
non-authoritatively.  Starting with 8.2, it appears to discard the zone
information completely, so it will typically respond with referral records,
and the client should then try a different server (but if all the slave
servers have expired the zone, it will eventually time out).

-- 
Barry Margolin, barmar at genuity.net
Genuity, Burlington, MA
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