Recommended values for a zone

Bob Harold rharolde at
Thu Jan 4 14:34:20 UTC 2018

On Wed, Jan 3, 2018 at 5:58 PM, Mik J <mikydevel at> wrote:

> Thank you Bob for your answer.
> I continued to search and saw rfc1912 page 4
> It's much higher than I first thought
> Le mercredi 3 janvier 2018 à 20:05:57 UTC+1, Bob Harold <
> rharolde at> a écrit :
> On Wed, Jan 3, 2018 at 1:57 PM, Mik J via bind-users <
> bind-users at> wrote:
> Hello,
> I would like to have your thoughts about what should be the best values
> for refresh, retry, expire and negative cache.
> In my case I have 2 DNS which are hosted in 2 different locations. These
> location are near one another (100km). The latency is very low and packet
> is 0.
> I configured a lot of zones on my DNS and they not master for someone else.
> This is a very simple setup in termes of master/slave.
> I would be tempted to
> * configure a high refresh period since I have notify configured on the
> master. What about 7200s ?
> * Configure a high retry period because I don't expect the master to be
> offline, what about 3600 ?
> * configure a expire very high like 2 days so that the DNS service would
> work even if the master is down
> * I don't have any opinion about the negative ttl yet but any advices are
> welcomed.
> What about your setups if it looks like mine ?
> Regards
> I typically use an expire time of 14 days or a month.  But that said, you
> need some way to get notified that zone transfers are failing.
> The refresh and retry are ok, but personally I would set them lower
> because they don't generate a lot of traffic, and a notify could get lost.
> It depends on how sensitive you are to extra traffic.
> Negative TTL depends partly on how fast you want new (or accidentally
> deleted) records to be usable.  I use 10 minutes.
> --
> Bob Harold

Thanks for mentioning rfc1912.  I just read it again, and the advice is
One update - I think that "minimum" is now used only as the TTL for
NXDOMAIN (domain name does not exist) replies.  The default TTL is set with
a $TTL record (usually at the top of the zone file).

Bob Harold
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