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msatter
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ROS DNS-client "ignoring" TTL set by own DNS server

Sun Aug 11, 2019 1:57 pm

When I make a static DNS entry and I look in Cache then I see it counting the TTL down for a few seconds and then it starts counting from the top again.

I have to move the static entries to an external DNS server to have a normal TTL countdown of the given TTL value.
Two RB760iGS (hEX S) in series. One does PPPoE and both do IKEv2.
Running:
RouterOS 6.46Beta / Winbox 3.19 / MikroTik APP 1.3.1
Having an Android device, use https://github.com/M66B/NetGuard/releases (no root required)
 
pe1chl
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Re: ROS DNS-client "ignoring" TTL set by own DNS server

Sun Aug 11, 2019 2:22 pm

Of course when the entry is static, the TTL in cache is meaningless. You can consider it as "blank" or "the configured TTL value".
It would be the same in an external DNS server (in the server itself, not in the cache in the router).
 
Sob
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Re: ROS DNS-client "ignoring" TTL set by own DNS server

Sun Aug 11, 2019 6:23 pm

It's just display problem, it's counting down in WinBox, but DNS responses always contain full configured TTL.
People who quote full posts should be spanked with ethernet cable. Some exceptions for multi-topic threads may apply.
 
pe1chl
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Re: ROS DNS-client "ignoring" TTL set by own DNS server

Sun Aug 11, 2019 9:29 pm

It appears that he is thinking that the correct behaviour is to count down.
But it isn't. The server that holds the actual information should always return the full TTL, and only caching resolvers should count down to zero and then remove the record.
As the MikroTik DNS service is the actual server for the static DNS records and not a caching resolver, the behavior to always return the same TTL is correct.

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