Never seen that error, but I think all it means is that the website's domain name (
www.nexon.net) did not or was unable to properly load on your browser?
DNS is Domain Name System which I believe is basically just a function in your browser that converts weird looking IP addresses like 201.123.456.78 to something more understandable to us like www.nexon.netIf that's the case you can do one of many things!
1) Refresh the browser
2) Visit another website then revisit
www.nexon.net3) Restart your browser
4) Update your browser
5) Install and use a different browser
6) Restart your computer
7) Check for known solutions in the internet from people who have the same problem.
8 ) Scan for Viruses? (could be virus that's messing you up)
9) System restore to the last time your computer was working fine!
If the problem persists it could be Nexon's website? Maybe they're having problems and their website is sending bad DNS information? xD
Anyway, that's something to keep in mind if that happens again!
I'm glad it was only a temporary problem and you have it fixed now!