default local DNS caching name server

Björn Persson bjorn at
Sun Apr 13 13:52:52 UTC 2014

William Brown wrote:
>In businesses, it's also common place to have a low-ish ttl (Say 5
>minutes) and when a system is migrated, they swap the A/AAAA records to
>the new system. The dns servers on the network are updated, but the
>workstation has the old record cached. Without a local cache, they
>would query the local server again, which is relatively cheap. IE: It
>keeps users happier even if they only needed to wait 5 minutes. Some
>people like things to be instant. 

If the admins on that network configured a five-minute TTL, it's because
they *want* the clients to cache the records for five minutes. They can
set the TTL to zero if they want the servers to be queried for every
single lookup.

And if they're migrating a system they will know this more than five
minutes in advance, so they can set a zero TTL temporarily.

Björn Persson
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