What does "Temporary failure in name resolution" acctually mean?

Have read quite a lot of questions about this problem, but everyone just explain how to solve it (which do not work for me) and none what I have found actually explain what the reason for it is. Personally I get this problem with my home network All The Time! Literally about 20 times a day and every time it happens it can last up to 3 months if I am unlucky.

My ISP say that it is a problem with my router, I have 2 routers now. One ASUS and one Linksys, the ASUS have default firmware and the Linksys have dd-wrt. I run 2 arch linux PCs and one Android smart phone. All devices get the same problem when it occurs. At the moment I use the Asus one because the Linksys never recovered while ASUS have internet access for about 5 min before loosing connection for about 10 min. Have borrowed a friends router and it is the same problem with that one. I can with all of them setup a LAN without any problem.

Is this a problem on my end or over at my ISP? I would really appreciate an answer for this because when I call them they say that I am doing something wrong and are responsible for it, but I honestly think they are to blame. When the internet goes down compleatly I can still share the wifi from my phone and it works, so do not believe I have miss configured the wifi on my PC's.

"Temporary failure in name" resolution means that your system thinks that the configuration for your name resolution is sane, but that it is unable to resolve names at this moment.

Most of the time, this is because the DNS server is not available for the system. That again may be caused by a very large number of reasons, from a faulty cable to ISP servers being down.

In general, debugging this has a number of steps:

• Can I ping the gateway on it's IP address?
• Can I ping other hosts on the network on their IP address?
• check what your DNS server is (8.8.8.8, your ISP's DNS, the router/gateway,...)

And, then depending on what your DNS sever is:

• If it is your own router/gateway, re-check the DNS settings on that device. Make sure that the source server is correct, recheck everything.

• If it is your own router/gateway, you might try with nmap to see if the port is open

• try

nslookup
server (your server's IP address)
test.com

If that works, the network part of the name resolution works and you need to look at your system's specifics.

If that doesn't work, try 8.8.8.8 as the server. If that works, there is something wrong with your normal DNS server.

There are of course many more causes of failure. I know of an ISP that redirects all DNS trafic towards its own DNS (to serve adds for non-existing hostnames). In that case other debugging actions may be necessary.