How to reduce the frequency of Name Server response tests

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How to reduce the frequency of Name Server response tests

James Moe-2
Hello,
  assp 2.5.5 ()
  linux 4.4.70-18.9-default x86_64
  perl 5.18.2

  ASSP tests the response of DNS name servers with unnecessary
frequency: usually every 5 minutes (or so) although there is a
occasional burst of 3 or 4 tests in a minute.
  Is there a way to permanently set the test interval to, say, every 4
hours?

--
James Moe
moe dot james at sohnen-moe dot com
520.743.3936
Think.

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Re: How to reduce the frequency of Name Server response tests

Thomas Eckardt/eck
>frequency: usually every 5 minutes (or so)

this is regulary done once in a minute

>although there is a
>occasional burst of 3 or 4 tests in a minute


only if at least one DNS-server does not answer and the availabe DNS-server count is less than the configured value - and there may be more DNS checks per minute in this case


>  Is there a way to permanently set the test interval to, say, every 4
>hours?

In theory yes - it is hard coded.

But NO. DNS queries are used for several checks. All checks for one mail can produce hundreds of dns queries. So, it is important for assp to know, which DNS-servers are available and how long it takes to query each of them. Most important is NOT to query any unavailable or slow answering DNS-server, because of the possibe timeout delay.

The hostname used to check the DNS-servers can be configured. Having a long TTL for this entry will force the DNS-server to answer from its cache in some milliseconds. Not a big deal in relation to (possibly) several thousand queries done in the minute before.

Keeps the question: Why should this query interval be changed?

Thomas




Von:        James Moe <[hidden email]>
An:        For Users of ASSP <[hidden email]>
Datum:        24.06.2017 20:36
Betreff:        [Assp-user] How to reduce the frequency of Name Server response tests




Hello,
 assp 2.5.5 ()
 linux 4.4.70-18.9-default x86_64
 perl 5.18.2

 ASSP tests the response of DNS name servers with unnecessary
frequency: usually every 5 minutes (or so) although there is a
occasional burst of 3 or 4 tests in a minute.
 Is there a way to permanently set the test interval to, say, every 4
hours?

--
James Moe
moe dot james at sohnen-moe dot com
520.743.3936
Think.

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Re: How to reduce the frequency of Name Server response tests

James Moe-2
On 06/24/2017 11:59 PM, Thomas Eckardt wrote:
>
> Keeps the question: Why should this query interval be changed?
>
  The localhost's name server is almost always the fastest responder,
mainly due to caching. The exception occurs when it must forward a
request to one of the ISP's names servers after which the result is
cached; the ISP's servers are the other two tested by ASSP.
  We have a very simple local network. Either the local name server has
it cached, or it forwards the request to one of the ISP's servers.
  While the once-a-minute burden is rather light, I do not see the point
of an essentially useless exercise given our system.
  Or I could just turn off the logging so I do not see it...

  This is what the logs show 99.5% of the time. 64.119.32.100 and .101
are forwardees for the local name server:

2017-06-25 12:58:07 Info: Name Server 127.0.0.1: ResponseTime = 2 ms for
sourceforge.net
2017-06-25 12:58:07 Info: Name Server 64.119.32.100: ResponseTime = 14
ms for sourceforge.net
2017-06-25 12:58:07 Info: Name Server 64.119.32.101: ResponseTime = 20
ms for sourceforge.net
2017-06-25 12:58:07 Info: Name Server 127.0.0.1: OK
2017-06-25 12:58:07 Info: Name Server 64.119.32.100: OK
2017-06-25 12:58:07 Info: Name Server 64.119.32.101: OK


--
James Moe
moe dot james at sohnen-moe dot com
520.743.3936
Think.

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Re: How to reduce the frequency of Name Server response tests

Thomas Eckardt/eck
switch off 'DNSResponseLog'

Thomas





Von:        James Moe <[hidden email]>
An:        [hidden email]
Datum:        25.06.2017 22:16
Betreff:        Re: [Assp-user] How to reduce the frequency of Name Server response tests




On 06/24/2017 11:59 PM, Thomas Eckardt wrote:
>
> Keeps the question: Why should this query interval be changed?
>
 The localhost's name server is almost always the fastest responder,
mainly due to caching. The exception occurs when it must forward a
request to one of the ISP's names servers after which the result is
cached; the ISP's servers are the other two tested by ASSP.
 We have a very simple local network. Either the local name server has
it cached, or it forwards the request to one of the ISP's servers.
 While the once-a-minute burden is rather light, I do not see the point
of an essentially useless exercise given our system.
 Or I could just turn off the logging so I do not see it...

 This is what the logs show 99.5% of the time. 64.119.32.100 and .101
are forwardees for the local name server:

2017-06-25 12:58:07 Info: Name Server 127.0.0.1: ResponseTime = 2 ms for
sourceforge.net
2017-06-25 12:58:07 Info: Name Server 64.119.32.100: ResponseTime = 14
ms for sourceforge.net
2017-06-25 12:58:07 Info: Name Server 64.119.32.101: ResponseTime = 20
ms for sourceforge.net
2017-06-25 12:58:07 Info: Name Server 127.0.0.1: OK
2017-06-25 12:58:07 Info: Name Server 64.119.32.100: OK
2017-06-25 12:58:07 Info: Name Server 64.119.32.101: OK


--
James Moe
moe dot james at sohnen-moe dot com
520.743.3936
Think.

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