Help required for TTL.

[Erik Aronesty]

 - I usually use 1 day (86400) for most domain names, and 10 minutes (600) for DHCP clients.  

 - A very low TTL will, generally, cause more queries against your DNS server.  A record queries average 150-250 bytes, depending on the length of your domain name.  This of course depends on how distributed your client base is, and how frequently the same client hits your server, etc.  Analysis log files is the only way to know exact traffic patterns.  In my experience, the effect of a high TTL is dramatic (up to 100 times in DNS traffic savings) on very busy web sites, where as on low-traffic web sites, the effect is barely noticeable.

 - You have to know the usage patterns of your users.  It's possible to write a good analysis program that simulates the increasing of the TTL to various levels, reduces the log hits from the same-ip for same-query accordingly, and accurately estimates the bandwidth savings. 

 - This sort of analysis is definitely worth it, if you are managing more than 10,000 domain names.



                - Erik



-----Original Message-----
From:	Salman Ahmed Hashmi. [SMTP:salmanah at super.net.pk]
Sent:	Sunday, February 25, 2001 6:44 PM
To:	Bind -users.
Subject:	Help required for TTL.


Good day,

Can anybody suggest,
While defining a feasible ttl value for a domain,

1)Is there any relation b/w the available bandwidth (i.e link capacity
)to nslookups ?....
And,
2)How can an adminstrator know which domain needs a faster update and
which domain is comparatively dormant for setting TTL value in the soa
records.

Regards