DNS Resolution issues


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1 hour ago, sergiol652 said:

I have been having issues with Sonarr Indexer not working, could this be related to the DNS issues so many people are having? I usually can reboot the server and it works again, but it's getting old and there are no solutions that I have found. I have changed the DNS server addresses from DHCP, to static and back and I keep running into this problem.

Possible, but unlikely if it is only Sonarr. Would need more information to help troubleshoot, which Sonarr container you are using for starters. Also, rather than rebooting your whole server, have you tried just restarting the container?

 

Verifying a DNS resolution issue with one container would also require getting into it's own shell, are you familiar with that? (it's easy after setting up the docker-shell script)

 

If it's binhex's Sonarr container I would highly recommend shifting your dialog to his support thread here.

 

Occasionally I see indexers not working in Sonarr/Radarr simply because the API's limit has been reached for whatever "request per time period" it is restricted to. Nothing to fix that particular issue aside from waiting.

 

Have you check for errors under System > Status & System > Log Files?

Screenshot_20210519-133230_Chrome.thumb.jpg.afd6024d6d5b8cd65a9236f57ccf6955.jpg

Edited by groot-stuff
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I had other issues besides indexers in sonarr. Docker containers show Update Status as Unavailable and I have to click on "Check for Updates to get the correct status. The Community Apps can't find the DNS Server so it doesn't start. Docker cannot update the apps. All these issues go away after I reboot the server. These issues started after I upgraded to 6.9.X Was working fine before. I just suspect that Unraid is having issues resolving the DNS server.

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16 minutes ago, sergiol652 said:

I had other issues besides indexers in sonarr. Docker containers show Update Status as Unavailable and I have to click on "Check for Updates to get the correct status. The Community Apps can't find the DNS Server so it doesn't start. Docker cannot update the apps. All these issues go away after I reboot the server. These issues started after I upgraded to 6.9.X Was working fine before. I just suspect that Unraid is having issues resolving the DNS server.

Trying to help here but you'll need to provide more information than just symptoms...

 

What DNS servers are you using?

 

Have you tried others? Which ones?

 

How long after a reboot can you resolve a domain? Minutes, hours, days?

 

Are you using an ISP provided modem/router or have your own equipment?

 

Do you have any "safe browsing" or security services included from your ISP? (like the person above)

 

Are you running through any VPN or proxy connections/services?

 

Are you able to ping 8.8.8.8 from the terminal when the problem is occuring? (that would rule out a more general loss of connectivity)

 

What other troubleshooting steps have you tried aside from just rebooting?

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  • 8 months later...

Not sure if this will be helpful for any future people, found this post while doing my own troubleshooting when this came up.

 

Was just having this issue on my server "randomly", did all my typical reboots, trying different DNS servers (Google, OpenDNS, Cloudflaare, etc) to no avail....  was going through my mind and thinking of stuff that's changed recently and I use a PfSense firewall and had installed "Avahi" package recently to allow one network (hardwire) to Chromecast to my other network (WiFi) and haven't noticed any issues since installing it... until I logged into my server, a few weeks later.. of course. :)

 

After removing the package and turning DNS to "manual" then back to "auto" seems to resolve it. (can also change it back to manual and works fine)

Avahi.PNG

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On 1/22/2022 at 10:59 PM, SpuriousIndices said:

Not sure if this will be helpful for any future people, found this post while doing my own troubleshooting when this came up.

 

After removing the package and turning DNS to "manual" then back to "auto" seems to resolve it. (can also change it back to manual and works fine)

 

 

This is helpful! Back to manual/auto in unraid or in pfsense?

 

Though I have problem that I cannot get reverse proxy with swag to work with name resolution to nextcloud. I have to use IP-adress instead of "nextcloud" in the proxy-conf file.. I think this is related somehow

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  • 2 months later...

I have now also come up against this problem.

 

ping google.co.uk starts immediately and has a nice 1 sec cadence.

ping bbc.co.uk starts slowly and takes a good few seconds per ping.

 

ping -n bbc.co.uk works as expected.

 

I've nailed it down to something around the mDNS stuff, as before its mentioned in the log everything is OK, once that starts up (well before the array starts) then it all falls over.

 

What is UnRAID doing with mDNS?

 

Edit: To clarify, SSH in and start the ping bbc.co.uk as soon as you can. It works OK for a few seconds until something else is done during the startup and then it goes slow.

 

Edit: Confirmed.

 

Pings start going slow just as this happens:

 

/etc/rc.d/rc.avahidaemon start

 

Running /etc/rc.d/rc.avahidaemon stop

 

Fixes it...

 

Edited by Interstellar
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  • 8 months later...

Doesn't solve the 5-6 seconds delay to start a ping problem. DNS settings are to use my router (192.168.0.1) as DNS server. Switchting to 8.8.8.8 oder 1.1.1.1 does not change anything. Ironically all my VMs running on that machine work perfectly fine. Only unraid itself has this massive delay in DNS resolution. Whats going on here. Stopping avahi no help. Removing /etc/resolv.conf and removing /boot/config/network.cfg, rebooting, resetting network. All of that no help.

telnet 8.8.8.8 53 works perfectly as it should. Pings (when they start after that 5-6 seconds delay) run at 5-7ms to google. Perfect. Bandwith test: 980mbit download, 510mbit upload (fiber ftth germany) works great. Having this problem for several weeks now. Anyone has an idea what to try next?

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2 hours ago, HackHome said:

Doesn't solve the 5-6 seconds delay to start a ping problem. DNS settings are to use my router (192.168.0.1) as DNS server. Switchting to 8.8.8.8 oder 1.1.1.1 does not change anything. Ironically all my VMs running on that machine work perfectly fine. Only unraid itself has this massive delay in DNS resolution. Whats going on here. Stopping avahi no help. Removing /etc/resolv.conf and removing /boot/config/network.cfg, rebooting, resetting network. All of that no help.

telnet 8.8.8.8 53 works perfectly as it should. Pings (when they start after that 5-6 seconds delay) run at 5-7ms to google. Perfect. Bandwith test: 980mbit download, 510mbit upload (fiber ftth germany) works great. Having this problem for several weeks now. Anyone has an idea what to try next?

 

What address are you pinging... a domain or an IP?

 

Are the results of these two commands the same? and same initial delay?

ping ns1.google.com

ping 216.239.32.10

 

Are the VM's being assigned their own IP addresses? Same subnet as host unRaid machine? Are they assigned the same or different DNS servers?

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8 hours ago, groot-stuff said:

 

What address are you pinging... a domain or an IP?

 

Are the results of these two commands the same? and same initial delay?

ping ns1.google.com

ping 216.239.32.10

 

Are the VM's being assigned their own IP addresses? Same subnet as host unRaid machine? Are they assigned the same or different DNS servers?

Pinging domain names only as only with domains I have the problem.

 

First command takes exactly 5 seconds until name resolving takes place and it starts to ping. Second command starts instantly.

 

VMs get IP from same Subnet 192.168.0.0/24 with same DNS Server provided (namely IP of Router 192.168.0.1). In the VMs i also can set 8.8.8.8 for example. same result. From within any VM it resolves instantly

Edited by HackHome
More precise
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On 9/13/2020 at 12:53 PM, groot-stuff said:

tcpdump command and options/filters I used to clean up the capture

- command: tcpdump -i any -nn -t -e dst not [IPofMachineYouAreOn] and src not [IPofMachineYouAreOn] -w [filename.pcap]
    - options: -i any (all interfaces), -nn (tcpdump tool will not do dns lookups), -t (user readable timestamps), -e (also get ethernet header)

    - filters: dst not [IPofMachineYourAreOn] and src not [IPofMachineYouAreOn] (filter out packets to/from the machine you are connected to unraid from)

    - output: -w [filename.pcap] (write to filename.pcap, .pcap is the standard extension for packet captures)

Tip: stopping dockers, vms and other processes that create network traffic is crucial to this effort as well

 

20 hours ago, HackHome said:

Pinging domain names only as only with domains I have the problem.

 

First command takes exactly 5 seconds until name resolving takes place and it starts to ping. Second command starts instantly.

 

VMs get IP from same Subnet 192.168.0.0/24 with same DNS Server provided (namely IP of Router 192.168.0.1). In the VMs i also can set 8.8.8.8 for example. same result. From within any VM it resolves instantly

 

I quoted part of my post from way earlier in the thread, the next thing I'd suggest is capturing some packets to inspect/investigate with WireShark or similar tool.

 

Just switch out the IP in the command below for the one of the machine you are using to SSH into unRaid with. Then take the .pcap file into WireShark and see if there are any oddities, feel free to share the .pcap if you'd like (DM it so you don't have to post potentially identifying IP info to the world).

 

tcpdump -i any -nn -t -e dst not 192.168.0.254 and src not 192.168.0.254 -w unraid.pcap

 

Refer to my older post for more info/instruction. Definitely make sure to reduce network traffic to clean up the tcpdump (turn off Dockers & VMs).

https://forums.unraid.net/topic/96835-dns-resolution-issues/?do=findComment&comment=892657

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