A Hosts file acts like a mini domain name server (DNS) on your computer. Your TCP connection will access it before going out to the internet to equate the written name (ResExcellence.com) with its internet IP address (207.208.148.74).
This saves time and can dramatically speedup access to commonly visited sites, like your mail and news servers. You can download a prepared Hosts file containing dozens of popular Macintosh sites. Place the file in your System Folder, add your own popular sites, and enjoy the increase in speed.
To add your ISP's mail and news servers, I recommend a great piece of freeware called What Route. Using it, you can convert your POP, SMTP, and news servers into IP addresses. Once you have the IP numbers, add the following lines to the Hosts file as shown in the example below:
pop.my_mail_server.com A 111.222.333.444
smtp.my_mail_server.com A 111.222.333.445
To add your news server, try something like:
news.my_news_server.com A 111.222.333.446
nntp.my_news_server.com A 111.222.333.447
There are several options to enhance the Hosts file. This Apple TIL has more information.
