Lately i was asked, if it's possible to run the SharePoint Central Administration if the application server hosting it is offline/dead.
So yes, It's Possible !
Consider the following simple 3-Tier Sharepoint Architecture farm
Here are there are three servers:
SharePoint Database Server :
This server contains the SQL server dedicated/Shared to the SharePoint 2010
Farm. It contains all the database for the Web Application/Service Applications residing in the SharePoint Farm.
Application Server :
This server contains the Central Administration Site hosted and all the other service applications running on it.
Web-Front End Server :
This server will act as the web-front end server. There can be more than 1 WFE server in a SharePoint Farm, where load balancer will balance the end-user request coming to the SharePoint farm to each of this servers.
So now at this point we have Central Administration site running on the application server. But what if the Application server is down ? Our site which has been hosted on the application server will be inactive and your sharepoint farm will be without Central Administration Site.
You can read more about this article over here