Hardware Reference
In-Depth Information
TABLE 3.5
Common protocol TCP ports
Protocol
Port
FTP
20 and 21
HTTP
80
HTTPS
443
POP3
110
SMTP
25
IMAP
143
DHCP
546 and 547(IPv6); 67 and
68 (IPv4) (also BOOTP)
DNS
53
You usually don't have to worry about the port assignments. One situation where you
may is if the network administrator in charge of some portion of your Internet experience
(such as your mail server) has decided to use a nonstandard port for one of the services.
In a case like that, you may need to go into the connection or account properties in the
application in which you use that service and specify the port being used.
Internet Connections
Adding Internet to the mix of computer networking introduces new types of hardware and
new sets of communication protocols to your computer literacy vocabulary. In this section,
you'll learn about the hardware and software involved in Internet connectivity as well as
some web browser features that employ other related protocols and technologies.
Hardware for Internet Connections
A decade or more ago, most people connected to their
Internet service provider (ISP)
via
a dial-up modem. A
modem
, short for modulator-demodulator, is an analog-to-digital and
digital-to-analog converter that translates digital computer data into sounds that can be
sent on a regular telephone line. Then another modem at the other end converts the analog
signal back to digital.
