I have the following set: use_dns(persist_only); dns_cache(yes); dns_cache_hosts(/etc/hosts); After I make a change to /etc/hosts, how long until syslog-ng will pick up the change?
Andrew Kerr wrote:
I have the following set: use_dns(persist_only); dns_cache(yes); dns_cache_hosts(/etc/hosts);
After I make a change to /etc/hosts, how long until syslog-ng will pick up the change?
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From the administrator's manual: dns_cache_expire() number 3600 Number of seconds while a successful lookup is cached. so you will either have to wait that many seconds (3600) by default or it will be instantaneous, depending on the behaviour of syslog-ng. So the question now becomes Does the /etc/hosts file bypass the cache the same way that the os does and make the change instantaneous? On linux for example any change made to the /etc/hosts file results in instant redirection to the new lookup result even when a name cache daemon is running, I would expect syslog-ng to do the same in some ways, although I wouldn't be surprised if it didn't for performance reasons... The line below from the administrator's manual implies that it would be instantaneous since if it bypasses dns then surely it doesn't use the dns_cache? "Name of a file in |/etc/hosts| format that contains static IP->hostname mappings. Use this option to resolve hostnames locally without using a DNS." -h -- Hari Sekhon
On Thu, 2008-05-15 at 09:27 +0100, Hari Sekhon wrote:
Andrew Kerr wrote:
I have the following set: use_dns(persist_only); dns_cache(yes); dns_cache_hosts(/etc/hosts);
After I make a change to /etc/hosts, how long until syslog-ng will pick up the change?
______________________________________________________________________________ Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng Documentation: http://www.balabit.com/support/documentation/?product=syslog-ng FAQ: http://www.campin.net/syslog-ng/faq.html
From the administrator's manual:
dns_cache_expire() number 3600 Number of seconds while a successful lookup is cached.
so you will either have to wait that many seconds (3600) by default or it will be instantaneous, depending on the behaviour of syslog-ng.
So the question now becomes
Does the /etc/hosts file bypass the cache the same way that the os does and make the change instantaneous?
any change to the /etc/hosts file triggers a reload into syslog-ng's cache. so yes, it is instantanous.
On linux for example any change made to the /etc/hosts file results in instant redirection to the new lookup result even when a name cache daemon is running, I would expect syslog-ng to do the same in some ways, although I wouldn't be surprised if it didn't for performance reasons...
The line below from the administrator's manual implies that it would be instantaneous since if it bypasses dns then surely it doesn't use the dns_cache?
"Name of a file in |/etc/hosts| format that contains static IP->hostname mappings. Use this option to resolve hostnames locally without using a DNS."
-h
-- Bazsi
participants (3)
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Andrew Kerr
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Balazs Scheidler
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Hari Sekhon