Likely causes of intermittent domain name resolution failure?

Question

I have a cheap Tenda N301 router and TP-Link TC-7610 modem. I also have a relatively inexpensive Internet plan and a Linux Mint computer.

I get intermittent failures to resolve a domain name. This is most common when running the automatic update manager (which must check a variety of software repositories), but occasionally also happens on some ordinary websites.

Retrying/refreshing usually works, though in the case of the update manager, I often just end up with a different name failing and need to keep retrying until everything has succeeded at least once. Also, I suspect this issue to be the cause of failure when running some Windows installers (in Wine) and various game-updaters.

I haven’t seen this issue on my phone when connected over Wi-Fi and I have seen sudden disconnections occasionally on a game console (with a wired connection), but the error messages aren’t clear as to whether DNS resolution is the cause.

Is this likely to be caused by my ISP, my modem, my router, or my computer? What can I do to narrow down a cause?

As far as DNS specific settings go, the computer has DNS set to “automatic” for both IPv4 and IPv6. This directs it to 192.168.0.1. Navigating there in a browser gets me my router’s config page. The router has DDNS disabled, and has its preferred DNS server… Also set to 192.168.0.1, with no alternative DNS server. I’m not sure what that indicates.

Answer 1

Having this

"The computer has DNS set to “automatic” for both IPv4 and IPv6

This means it gets the DNS IP address or addresses from the DHCP server - The DHCP server is most likely to be your router.

You say that the router (192.168.0.1) has its DNS server set to itself (192.168.0.1) - That should not be so, I looked at the manual for your router and in the example they show the DNS is the same as the gateway for the router not the router

So perhaps you are looking at the LAN DHCP settings ? Which I show lower down as in this place I would expect the DNS to be the router.

In any case changing the DHCP settings on the router will enable you to configure the DNS servers for every device on your network so this may be simpler than changing it individually on each device.

On your router it is under “Administration > LAN Parameters” (section 3.83 of the user manual), type the addresses suggested by others into the Preferred and Alternate DNS servers, (I’ve included a screenshot of the manual page) save the settings, then disconnect and reconnect your PC and it should get the new DNS servers as its settings.

Answer 2

Try changing DNS revolvers at your router. Many ISPs have bad, unstable DNS resolvers. This should be possible even if your router uses DHCP in most cases. For starters try putting the following DNSes and see if things improve:

• Google DNSes: 8.8.8.8, 8.8.4.4
• Quad9: 9.9.9.9

Here is more detailed DNS public dns list:

https://www.lifewire.com/free-and-public-dns-servers-2626062

Always set more than one dns, even the best fail sometimes, if you have backup your router will use it in case first fails. Even if they don't fail your route/connection to them may briefly fail.

If that does not help I would look up for router firmware update, it might be e bug in your router.

To bypass the router entirely you might want to set the dns resolvers directly on your PC (8.8.8.8 for exemple) bc your router will usually proxy the DNS requests and give your devices its own address as DNS resolver. Check the network settings of your PC, if DNS is something like 192.168.x.x then thats your router.