Glossary
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dress and the notification of the new IP address, the com-
puter can always be reached at the selected domain
name.
Dynamic IP
Address
A dynamic IP address is an IP address valid only for the
duration of one Internet or network session.
Every computer participating in the Internet must have a
uniquely assigned public IP address. Since only a limited
number of such IP addresses is available, they must be
used sparingly. That is why most of the Internet partici-
pants who dial in to the Internet receive a dynamic IP ad-
dress. They are called dynamic because every participant
receives a new public address that has not been assigned
yet each time she or he dials in to the Internet.
By contrast, dynamic addresses are usually used in local
IP networks because they are easy to handle, and because
using them avoids incorrect IP address entries or uninten-
tional double assignments. The DHCP service is responsi-
ble for assigning unique dynamic IP addresses.
FAQ
abbreviation for Frequently Asked Questions
FAQs are collections with answers to frequently asked
questions on a certain subject area.
Fixed IP address
Fixed IP addresses are IP addresses which are permanent-
ly assigned to a computer or another device like a network
printer.
Assigning fixed IP addresses makes sense in cases where
a local network has a sufficiently large pool of IP address-
es available, or when a computer is always supposed to
be accessible at a certain address (such as a web server or
e-mail server).
Firewall
A firewall protects a computer or local network against at-
tacks from the Internet.
Most firewalls work with packet filters, which merely
check the IP addresses and port numbers of incoming and
outgoing data packets and filter the packets according to
prescribed rules.
