Some computers here at work are not being able to access different websites. For instances when they type in ESPN.com a page comes up from what looks to be go daddy saying this page is parked free. Other various websites do the same thing. I looked on google but couldn't find much that made sense to fix this issue. Anyone have any ideas on how to fix this?

Thanks

9/10/2008 12:26:27 PM

sure you typed in espn.com correctly? if you type in eespn.com or something, you'll get another site

9/10/2008 12:30:45 PM

yeah it is happening on a bunch of different computers...mine is ok but it is just all sorts of websites.

9/10/2008 12:32:20 PM

Your DNS is fubared. How are your local DNS servers set up? What DNS server /OS are they? Are you using forwarders? Who are the forwarders you're using?

9/10/2008 12:36:29 PM

ipconfig /flushdns

9/10/2008 12:42:04 PM

^ Our IT is gone for the week so not sure if that is somethign we can do on each of our machines or if we need to wait or what?

9/10/2008 12:44:32 PM

doing it on my computer now on tons of sites. Here is a screen shot of what it is saying. Any other ideas besides the ipconfig /flushdns or is it something related to the server side of things probably?

9/10/2008 1:13:32 PM

guys I think we've got a hacker

9/10/2008 1:30:20 PM

My first guess is that your local DNS servers are using forwarders supplied by your ISP for DNS lookups. So when your client machine tries to lookup say espn.com, it goes like this.

1 client checks local cache for espn.com
2 if it has it in the local cache, it use the local cache, otherwise ask local DNS server
3 client asks local DNS for espn.com
4 if local DNS has it cached, it returns it to the client, otherwise ask forwarder server
5 the DNS server you're using as a forwarder is probably owned by your isp and will continue to do lookups in cache or ask other servers until it gets a result which it then passes down the chain.

Once each hop gets a result back, it caches locally. Cache can be cleared at every point. The only points you have access to are on the client and your local DNS servers. Clearing the cache on your local DNS server depends on the server. If its the windows DNS server you just open the DNS tool, right click the server, and then clear cache.

What I think is happening in your case is after your local DNS asks the forwarder, the forwarder is either failing or has garbage further up stream. This is getting sent back to you and cached in your system.

So how do you fix it?

First determine if it even is DNS. Goto http://network-tools.com/ and do a lookup for the address thats getting the bad page. Grab the IP address and put it into your browser. If it goes to the right page, your issue is DNS. If it doesn't go to the right page something else is boned. Just one thing to note, ESPN.com is a shitty test case since their webserver seems to host more than espn.com Its dependent on client side dns (which is really stupid) so if you were to go to http://199.181.132.250 it probably wont go to ESPN.com. If it does redirect you to go.com your issue is DNS. Otherwise i would find another site to test.

If you do determine that its DNS, first just flush the DNS cache on your local server and then flush it on the client and try again. If that works it means something was fubared but is now fixed. Flush dns on all the clients and you should be fine. If it doesn't work after that, determine if you're using forwarders. Figuring that out depends on what DNS server you're using. If you do find the forwarders, determine if they belong to your isp. If they do, call your isp and have them figure it out because its their problem. If its not your ISP's forwarders either change it to your ISPs forwarders or get rid of the forwarders entirely.

Ultimately in this day and age no one should be using forwarders unless you pay for x ammount of bandwidth used. Any modern DNS server is going to be able to cache results from lookups sent directly to the roots. By adding the forwarders you create an extra, needless point of failover.


tl;dr. Short term fix see if clearing local DNS server cache works, if not call ISP and have them fix their forwarders. Long term fix stop using forwarders.

9/10/2008 1:46:19 PM

^ Thanks for that info. It definately is DNS issue using that method. And people can use that work around to access sites until IT guy gets back to fix the server side of things.

9/10/2008 2:06:04 PM

workaround:

set your computer to do dns lookups via 208.67.222.222 and 208.67.220.220 instead of using the dhcp-supplied servers

9/10/2008 2:22:03 PM