How can a farm still be running at all if the only app server is not reachable from the only SQL server? Can the Central Admin page be displaying incorrect information, or can the settings be cached in some manner?
The SP admin says the site is up and the only problem reported by users is the lack of any search results.
Helping a another company with their SP farm. The symptom they initially reported what that search was finding zero results sitewide. I looked at the crawl logs and found thousands of errors related to a Dev server that (somehow) got connected to their production environment. I told them, they were appropriately horrified, and said they would take care of it. Case closed.
...or so I thought. They called me again today and said there were still no search results. I checked again and found the same errors. They said they "fixed" the issue by physically turning off the development server.
Here's the mystery for me. The CA 'Servers in Farm' screen shows the Dev box as providing 100% of the app server duties. From the SQL server I tried both ping and UNC, using DNS name and IP, and all failed (as they would if the server was indeed powered off).