TTLs on A records?

online-reg online-reg at
Thu Apr 30 22:29:01 UTC 2009

Hi All:  I'm running Bind 9.5.0-P1 / Fedora on my primary NS.

Are TTLs on individual A records universally supported?

I have a domain with a TTL of "3h", and I wanted to route traffic between 
two servers in that domain quickly, so I set the TTL to the A record like:

www    300    A
;www    300    A

so I could uncomment one and comment the other to manually switch between 

I've had that setup for several weeks during testing...and I just reversed 
the records, incremented the serial, and reloaded BIND.

On my secondary NS (Bind 9.5.0-P1 / Freebsd 7), when I dig the "www" record, 
I see the TTL counting down from 300 (Cool!), and after it reaches "0", the 
IP address resets to the new one....perfect!

On my Windows DC (server2008), the change was also picked up after 5 

When I use some other lookup services, however (like, the old 
IP address shows up for much it's caching it and ignoring the 
TTL for the record. Should I expect that behavior?


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