UPDATE: our server people just came back to me with this reply. Can anyone help this front end developer translate this?
We are reviewing your case to see what the issue is. Application pool simply provides an environment for the site under which its processes run. When any process under the pool is not running properly, then it affects the application pool and the sites using this pool. When the portal website.org is down, you should be experiencing issues with website.devsite.org as well. Once the application pool is recycled, the site and processes (modules, skin etc) used by it also get restarted. So when the pool is recycled the site works for some time until the faulty process is initiated again.
I have checked the Event Viewer in the server to see if I can find any errors that can be helpful in fixing the issue. However, I can see nothing other than some warning messages for your site. I do not suppose the warnings are the cause for your site to go down, but I am not sure at this point. Following is what I see in the logs (I have pasted some basic information).
Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 7/21/2014 4:11:26 PM
Application Virtual Path: /
Application Path: C:\inetpub\vhosts\website.devsite.org\httpdocs\
Exception type: HttpException
Exception message: A potentially dangerous Request.Path value was detected from the client (:).
at System.Web.HttpApplication.PipelineStepManager.ValidateHelper(HttpContext context)
Request URL: http://www.maindomain/Support/hhttp:/...
User host address: 184.108.40.206
Is authenticated: False
You might need to check the applications that you are running under this site which might cause the issue. This is something that would need to be done from your end. If the issue started occurring after you made any changes to the site,then you would want to review the changes that were made. It is also recommended to get in touch with a DNN expert to have the site checked. Also, when the site goes down next time, let us know the approximate time at which you experienced the issue.
Please someone advise.