Chapter 59. Sockets: Internet Domains

Having looked at generic sockets concepts and the TCP/IP protocol suite in previous chapters, we are now ready in this chapter to look at programming with sockets in the IPv4 (AF_INET) and IPv6 (AF_INET6) domains.

As noted in Chapter 58, Internet domain socket addresses consist of an IP address and a port number. Although computers use binary representations of IP addresses and port numbers, humans are much better at dealing with names than with numbers. Therefore, we describe the techniques used to identify host computers and ports using names. We also examine the use of library functions to obtain the IP address(es) for a particular hostname and the port number that corresponds to a particular service name. Our discussion of hostnames includes a description of the Domain Name System (DNS), which implements a distributed database that maps hostnames to IP addresses and vice versa.