Bind : Zone forward type without cache

junix57 · 02-13-2012, 02:34 AM

Hello,

We currently have two separate dns servers due to migration.
The first runs in 129.200.0.0 toto.lu
the second manages tata.ad in 10.10.0.0

in the named.conf toto.lu

Code:

zone "tata.ad" in {
        type forward;
        forward only;

If I search from the dns which manages toto.lu
tortue.tata.ad -> 10.10.1.23 it returns me the correct one ip.

The problem is that toto.lu keeps a cache of my request to the SOA tata.lu I guess.

So I change tortue.tata.ad -> 10.10.1.25

the dns server always returns me toto.lu tortue.tata.ad -> 10.10.1.23
unless I force a flush rndc

there is there a way to say that for the area toto.ad there is no cache or it must forward the request?

I think to add in my options bind : additional-from-cache no ;
It's correct ?

thank you, Jerome

bathory · 02-13-2012, 03:30 AM

Hi,

I think you need to use max-cache-ttl and max-ncache-ttl with appropriate small values. Note that the values are in seconds.

Regards

junix57 · 02-13-2012, 04:05 AM

In default we have :

expiry time : 604800 (168hr)
refresh time : 21600 (6hr)
domain retry time : 3600 (1hr)
default TTL : 86400 (24hr)
Negative Cache TTL : 600 (10min)

For example, just modify :
default TTL : 3600 (1hr)
Negative Cache TTL : 60 (1min)

junix57 · 02-13-2012, 05:24 AM

What is risk if I modify for this :

default TTL : 60 (1 min)
Negative Cache TTL : 60 (1min)

bathory · 02-13-2012, 05:58 AM

Quote:

Originally Posted by junix57

What is risk if I modify for this :

default TTL : 60 (1 min)
Negative Cache TTL : 60 (1min)

There is no risk. The record will remain in client's cache for one minute and then it will expire.
Of course after migration you should use a value like 86400 (1d)

junix57 · 02-14-2012, 02:12 AM

Thanks for your explain :-)