Below are a couple of ways to figure out the apache web server version (on either windows or linux)
1. Simplest – execute the command “httpd -v”. httpd is the Apache HyperText Transfer Protocol (HTTP) server program.
Sample output –
Server version: Apache/2.2.17 (Win32)
Server built: Oct 18 2010 01:58:12
This would require you to login to the web server machine or putty it (in case of linux)