1. Login to your dedicated server as root user.
2. Use the following command:
# /usr/local/apache/bin/httpd -v
Server version: Apache/2.2.16 (Unix)
Server built: Feb 6 2012 11:41:41
OR
# httpd -v
Server version: Apache/2.2.16 (Unix)
Server built: Feb 6 2012 11:41:41