question about DNS server BIND 9

['chris']

hi

can someone explain please
..........................
recursion yes;
..........................
and
............................................
heartbeat-interval 2880;
............................................

from the BIND 9.2.X config file ?

regards
chris

[Ranjith_5 · Accepted solution]

DNS Recursion
======================================

DNS requests can either be "recursive" or "non-recursive".

Client applications typically requests that the DNS server performs recursion for them by setting an "RD" (recursion desired) flag in the request packet. This is a recursive request.
Client applications do this both because they do not posses the ability to resolve domain names themselves, and also to take advantage of centralized caching on the DNS server.

However, when a DNS server sends requests to other DNS servers as part of the recursion process, these requests are typically non-recursive (the RD flag is not set).

The DNS server indicates back to the client if it is willing to perform recursion or not by setting or not setting an "RA" (recursion available) flag in the response packet.

When a DNS server receives a recursive request from a client that it is willing to perform recursion for, it will go through the process of resolving the requested domain name by first asking the root servers, which respond with a referral to the top level DNS servers, then asking one of those servers, which respond with a referral to the next level DNS servers, etc.

When a DNS server receives a non-recursive request or a request from a client that it is not willing to perform recursion for, it simply responds immediately with whatever local data is has available at the time without doing any additional processing.

Obviously a recursive request requires a lot more processing by the server compared to a non-recursive request.
So it is important to configure Simple DNS Plus to only offer recursion to trusted clients.
You can configure this in the Options dialog / DNS security tab.
NOTE: For programs like browsers and e-mail clients to work, they must have access to a DNS server that offers recursion. Therefore local computers (including the server itself) should always be offered recursion

See http://www.jhsoft.com/help/index.html?df_recursion.htm


heartbeat-interval

=========================================
[ heartbeat-interval number; ]

heartbeat-interval defines the time in MINUTES when zones marked as dialup are updated (the dialup option is not yet supported in BIND). The default is 60 (1 hour), if specified as 0 NO updating will be performed. The maximum value is 40320 (28 days). This option may only be specified in a 'global' options statement

http://www.zytrax.com/books/dns/ch7/periodic.html

regards,
Syam

['chris']

thanks,

but should I enable these 2 options:

recursion yes;
heartbeat-interval X;

for an internal DNS Server BIND 9 (DDNS)
setuped for WIN2000 clients ?

[Hoang Chi Cong_1]

Hi chris
Hi Chang.

You can refer to this link, it may help you in some case:
http://www.intac.com/~cdp/cptd-faq/

Best and regard,
HAPPY NEW YEAR
HoangChiCong

[rick jones]

Clients probably do not care about heartbeat intervals - clients don't exchange zones with servers, that is server to server stuff.

As for recursion - is your DNS server supposed to be a caching server for the clients? If so, you probably want to allow recursion - IIRC that will then enable the DNS server to cache the requests' responses so they do not have to go out onto the net as often. Without the recursion, the clients will simply be redirected t the server(s) with the answers as already described.