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DNS entry issue? Archived From: Computers

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   posted: May. 21, 2008 @ 7:11p
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I have a web-based application accessible from http://apps.websitename.com. When one accesses this URL, a request is redirected to one of the 3 servers: http://server1.websitename.com, http://server2.websitename.com or http://server3.websitename.com. Now, the problem is with an AJAX request (with a twist). Lately because of a power outage, computer shuts down by itself. Upon opening an app using http://apps.websitename.com, it gives a JavaScript error. If I hit the app using one of the 3 servers directly, the app works fine. If the same user accesses the same app on a different computer - everything is fine.

I'm not sure what exactly is going on and obviously how to fix it. I have a suspicion that a DNS entry is getting corrupted for a specific user on his computer. I tried cleaning the cookies and Internet/temp files.

Dmitriy

   posted: May. 21, 2008 @ 7:11p

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   posted: May. 21, 2008 @ 7:29p
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dmitriy1980 said:Lately because of a power outage, computer shuts down by itself.

which system shuts down?

   posted: May. 21, 2008 @ 7:45p
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User's desktop. Win XP with SP2 and all the latest patches.

   posted: May. 21, 2008 @ 9:38p
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what's the javascript error? does the system shut off randomly now, or do you get power outages randomly that cause it to shut off?

   posted: May. 21, 2008 @ 10:21p
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I believe it says "No data found", however, it has nothing to do with the data as it works from another computer. Not sure what your second question mean. We get power outage very often and when it happens PCs are shut off because we don't have surge protectors.

Hope this helps.

   posted: May. 22, 2008 @ 6:32a
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So when the XP Pro with SP2 user accesses this site he gets a JavaScript error and then the machine shuts off? Does it do a proper Windows shut down? Or do you mean it reboots? If it is rebooting you should turn off auto restart so you can see what BSOD you are getting.

And I'm not clear - what did the recent power outage have to do with this?

   posted: May. 22, 2008 @ 6:44a
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" he gets a JavaScript error and then the machine shuts off..." is a wrong statement. He's what's happening. A user is using an app and all of a sudden there's a power outage where the computer is shut off (not restarted) - improper shutdown. After the power come back in 5-10 minutes, the user boots his computer and eventually opens up an app that he needs to work on. When he goes to the app, then he gets an error message stated in the previous post.

Hope this is clearer

   posted: May. 22, 2008 @ 6:57a
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Oh. Yes, that is much different.

So, does the error go away after another reboot? Does the error only happen this one time, right after the power failure induced reboot? Or is this error always happening now on this machine?

Also, if power failures are as common as you stated, why aren't you using a UPS?

   posted: May. 22, 2008 @ 8:37a
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This error does not go away after reboots. This error always happening now on this machine (or I have to say in this user's computer profile). If we create a new computer profile everything is back to normal. When you have 30-40 computers affected every day, recreating a profile is not an answer and I don't believe profile is getting corrupted, so I don't think the problem is with a profile.

As far as UPS, it's not my call. I did propose this to the management multiple times, but no one listens. They do have UPSs on PROD servers though.

   posted: May. 22, 2008 @ 8:47a
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it's a shame when they don't listen...

Anyway, if it is only on that profile why are you saying the profile is not corrupt? Maybe not the whole profile, but certainly something to do with how your script works is corrupt in that profile.

I don't know enough about JavaScript to know where those settings are stored, but I would imagine that you need to find those settings in that user's profile and wipe them out so they can be reset next time the user connects.

   posted: May. 22, 2008 @ 9:34a
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Makes sense, but I was hoping someone in this forum will point me to the right place where DNS entries are set in the user's profile. As far as JS, I know that it stores all the files in the Temporary Internet Files, however, how and why it affects a DNS entry, I don't know.

   posted: May. 22, 2008 @ 12:04p
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the dns info is most likely handed out by the dhcp server every time the system gets a new ip address. if you can get to anything else by name, like google.com or a different server, it doesn't really sound like a dns issue. it sounds more like a corrupt cache type problem.

have you tried clearing the cache (temp internet files), including all offline content?

does the problem still occur if you try a different browser like firefox?

have you had any systems powered off while they were NOT in the web app?

do those systems have the same issue on reboot?

   posted: May. 22, 2008 @ 12:52p
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@Tresh

1) have you tried clearing the cache (temp internet files), including all offline content? yes, i deleted the cookies, cache, offline content and temp files

2) does the problem still occur if you try a different browser like firefox? Our app only supports IE (it's internal app)

3) have you had any systems powered off while they were NOT in the web app? not sure what you're asking

4) do those systems have the same issue on reboot? Again not sure what you mean, but as I mentioned in the previous posts, when the power goes off, desktop is not restarted, it's shut down. Power outages that we have are not for 1-2 seconds, they last in minutes, so desktops are never restarted by themselves.

   posted: Jun. 22, 2008 @ 5:10p
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any other ideas?

   posted: Jun. 22, 2008 @ 5:40p
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Just to eliminate the whole IP / DNS issue, how about editing the HOSTS file and pointing right at those servers with their correct IP? If the issue still happens you know for sure that's not the problem. If it goes away, fine - leave the HOSTS file and maybe copy it to all the other machines to keep the issue from happening again.

   posted: Jun. 22, 2008 @ 5:46p
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are you saying to put 'http://server1.websitename.com, http://server2.websitename.com and http://server3.websitename.com's IP address into the hosts file or http://apps.websitename.com's IP?

   posted: Jun. 22, 2008 @ 6:55p
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Well, I'm not sure where the problem is happening, so I would probably try apps first and if that didn't help try adding the other 3 as well. Or do all of them - I guess it's just a matter of whether you want to try to pin the issue down or not. If you just want a fix then it doesn't matter if you know which it is or not, so do all 4 and be done with it.

If it is not a name resolution issue it won't matter anyway.

   posted: Jul. 1, 2008 @ 7:48p
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Whats your DNS TTL?

Whats your APP's session TTL?

I believe they should match. Server may be expecting the session-cookie due to inactivity timer not yet expiring and the DNS Record on the user desktop hasnt expired yet so it goes back to server1 and tries to re-establish connection to the app server1 doesnt have the ability to read the session cookie.

"No data found" might be a session cookie read command failing, as in I tried to read this session cookie and the No data was found because that session cookie was in memory and is GONE from the client's machine after crash/reboot.

I know nothing about AJAX and very little about web programming in general, but I know session cookies and load balancers (in your case DNS Round robin it sounds like) can cause headaches when the timing's arent lined up.

 

You could try recreating this by using Task Manager or something to forcibly kill the browser executable. Then fire up the browser again and see if you have the same problem.


Cached DNS Entries can be displayed on Windows with this command: ipconfig /displaydns
DNS Cache can be wiped out with this one: ipconfig /flushdns


Anyway, hope this helps you find your problem. Post back if you figure it out.

   posted: Jul. 1, 2008 @ 10:09p
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Sounds more like a virus problem then dns issues, I dont see your dns entries getting corrupted along with hes been rebooting.

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