Temporarily lost connection to web but somehow not to skype

[Modax]

Can anyone explain this? For around 15 minutes this morning my laptop couldn't connect to any website, (I tried about a dozen sites and everything came up as 'page cannot be displayed, DNS not found') but somehow at the same time skype was working normally and i was talking to my friend. I don't understand why an internet connection which is working just fine for a skype call would just stop processing requests for webpages 15 minutes.

[Edi]

The DNS not found is the reason right there. Your computer lost its connection to the DNS server, which is the thing that tells the computer to connect to x.x.x.x (the IP address) that corresponds to www.whatever.com where you wanted to go.

The reason for the DNS connection loss may be anything from your ADSL/cable modem router to something else. If the reason is your router (for example, I run into the case of people having older A-Link RR24 modems sometimes and those are notorious for not forwarding DNS responses back to the computer), you can get around it by putting the DNS settings directly into your computer's network settings. Recommended to do that only if you have a desktop. You can get the DNS server addresses from your ISP or you can use something like OpenDNS which doesn't care who your ISP is.

[Modax]

Thanks for the reply - so the web and email use DNS but Skype uses something else? Since today is the first time I've noticed this issue, I'm not going to do anything to my router (and I haven't so much as touched it today so I'm pretty didn't do anything to cause the problem). What would be an example of 'Something else'? The ISP doing maintenance work/fiddling with something?

[TheFeniX]

The ISP doing maintenance work/fiddling with something?

My friend in Germany had this issue twice. He would lose connection to Teamspeak, Ventrillo, and any online game. However, he could still browse the web and connect through Skype. Both times this happened he had just finished downloading two large games (STO and WoW). It took about 30 minutes for it to reconnect. I can only assume his provider throttled his bandwidth on anything that wasn't port 80 and possibly Skype due to it's prevalent use.

If this happens again, there's a few things you can try. Open a command prompt (start > run > CMD) and use ipconfig /all
Look under IPv4 for your DNS server address. This is likely just your router as most do DNS forwarding, but if it isn't try pinging it with "ping <ip address>" If you care to try, your router itself should have the ISP DNS servers listed under it WAN connection. Or you can just call your ISP and ask them what the IPs are.

Another easy way to test if DNS is working is to do something like ping http://www.google.com or any other popular website. If it resolves to an address, but isn't responding: using "tracert www.google.com" will show where your packets are "dieing." Now, some ISPs don't like tracert, so this may not do you much good, but if you can get past the first few hops, then you know the issue isn't on your end or your ISPs end.

NOTE: the forum is breaking my formatting and I don't feel like using /code. Just don't use the http : // when doing pings or tracing routes.

[Modax]

Thanks - I will try your "tracert www.google.com' command if this happens again.

[Edi]

One of the reasons why your Skype worked might well be if there is some hardcoded IP address for a Skype server in the program itself or something similar, in which case it does not need to rely on the operating system's DNS settings to get where it needs to go.

another solution is set your modem/router to bridge mode and you won't lose DNS unless the server goes down, but it exposes your computer to greater risk of infection by malware.

[Ariphaos]

Most IM programs will only use DNS on startup, the first time they connect, using the raw ip from then on. This makes it easy to help people get onto e.g. Google DNS or some other DNS service in the mean time.

[madd0ct0r]

skype uses it's own servers.

if you're paranoid, it might have been somebody diverting the traffic for inspection. the initial block on facebook here was set at DNS level, so you just had to change the DNS code your computer looked for to google's code.

[TheFeniX]

Most IM programs will only use DNS on startup, the first time they connect, using the raw ip from then on. This makes it easy to help people get onto e.g. Google DNS or some other DNS service in the mean time.

Skype also uses a lot of Peer-to-Peer. Since, I believe, the master list is only IP Addresses, this makes it even more stable if there's connectivity issues.