Here is a link to one post on ssh config file.
However, if you want entries for lot of servers with their IPs or names, then it could be cumbersome to add all the entries in the .ssh/config file. So, here is a shortcut notation:
Host 1 2 3 4 5 6 Hostname 192.168.1.%h User Ciphers arcfour where '%h' denotes the IP that you use in the ssh command. The following escape character substitutions will be performed: ‘%d’ (local user's home directory), ‘%h’ (remote host name), ‘%l’ (local host name), ‘%n’ (host name as provided on the command line), ‘%p’ (remote port), ‘%r’ (remote user name) or ‘%u’ (local user name).