Previous parts of this book have focused on coherent collections of topics, such as file sharing servers or login servers. This section, though, examines a few networking “stragglers”—servers that aren’t easily grouped together with similar tools. Chapter 13 covers mail servers, using the Simple Mail Transfer Protocol (SMTP), the Post Office Protocol (POP), and the Internet Message Access Protocol (IMAP). Chapter 14 describes using Linux as a backup server—a system that’s used to back up other computers on a network. Finally, Chapter 15 describes several miscellaneous servers—specifically, a Dynamic Host Configuration Protocol (DHCP) server, Domain Name System (DNS) servers, and Network Time Protocol (NTP) servers.
Many of the servers and protocols described in this part of the book are themselves quite complex, and entire books have been written about most of them. Thus, these servers and protocols are in no way trivial or unimportant. The intent of this part of the book is to introduce the basics of configuring the servers described and to illustrate where such servers can fit in a network. You should be able to get any of these servers working in a basic way after reading the relevant chapter, but for more advanced configurations, you may need to consult server-specific documentation.