TTL in DNS cache-only

Edward Lewis Ed.Lewis at neustar.biz
Fri Oct 27 19:21:24 UTC 2006


The authoritative server sets the TTL in the 
record but what is used in the cache can be 
slightly altered as described in the BIND ARM 
(found under the doc subdirectory in the distro), 
chapter 6 [from BIND version 9.3.2]:

max-ncache-ttl
To reduce network traffic and increase 
performance the server stores negative answers. 
max-ncache-ttl is used to set a maximum retention 
time for these answers in the server in seconds. 
The default max-ncache-ttl is 10800 seconds (3 
hours). max-ncache-ttl cannot exceed 7 days and 
will be silently truncated to 7 days if set to a 
greater value.

max-cache-ttl
max-cache-ttl sets the maximum time for which the 
server will cache ordinary (positive) answers. 
The default is one week (7 days).


At 15:12 -0400 10/27/06, qipman wrote:
>The TTL is defined by the authoritative name server.
>
>-----Original Message-----
>From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
>Behalf Of afaf el maayati
>Sent: Friday, October 27, 2006 5:30 AM
>To: bind-users-bounce at isc.org; bind-users at isc.org
>Subject: TTL in DNS cache-only
>
>Hello;
>
>   I have a question about the time during a DNS Server (DNS cache-only)
>can
>keep information in its memory,  This duration corresponds to the TTL as
>
>mentioned in the authoritative DNS server, or the DNS server has its own
>
>duration?
>
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-- 
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Edward Lewis                                                +1-571-434-5468
NeuStar

Secrets of Success #107: Why arrive at 7am for the good parking space?
Come in at 11am while the early birds drive out to lunch.



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