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Why XG asks not configured DNS servers?

Hi,

noticed this behavior:
- XG configured for 3 DNS servers
- on upstream device only those 3 DNS servers are allowed for XG
- occasionally XG sends DNS request to many other DNS servers and these are denied by upstream device
- issue on 18.5.1 and actual 18.5.2 too (observed that on prior versions too)
- XG running as MTA and web proxy only

- when looking to such requests, that were PTR queries only

Not sure what triggers this behavior during operation.

I was able to replicate this behavior when cable was plugged out and then back in to the device.

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0 rfcat_vk over 2 years ago

Hi Tomas,

do you block you internal devices from sending DNS requests? I have some device and some applications that ignore the PC/MAC DNS settings, they do eventually fall back to the device DNS settings.

Ian

XG115W - v20 GA - Home

XG on VM 8 - v20 GA

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0 LuCar Toni over 2 years ago in reply to rfcat_vk

Check the logviewer, if you find the root cause of those connections. Who actually building up those connections.

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0 Tomas Beran over 2 years ago in reply to LuCar Toni

I do not know what is triggering it and haven't found anything specific. Today I started seeing the logs after I logged in to GUI to check logs. As I wrote above, even interface down/up can trigger that.

Noticed too that sometimes it takes few hours of such logs, sometimes just minutes.
To stop these logs I go in GUI to DNS page and 'apply' the settings again (no change at all).
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0 Tomas Beran over 2 years ago in reply to Tomas Beran

As noted, it was just about PTR queries
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0 Tomas Beran over 2 years ago in reply to Tomas Beran

Just review the IPs and seem the queries are for root servers. Some examples:
192.203.230.10     e.root-servers.net
128.63.2.53            h.root-servers.net
199.7.83.42            l.root-servers.net

....
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0 Tomas Beran over 2 years ago in reply to Tomas Beran

Just review the IPs and seem the queries are for root servers. Some examples:
192.203.230.10     e.root-servers.net
128.63.2.53            h.root-servers.net
199.7.83.42            l.root-servers.net

....
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