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Appendix C Glossary
Glossary
Description
DSL(Digital Subscriber
Line)
A technology that allows data to be sent or received over
existing traditional phone lines.
ALG
（
Application Layer
Gateway
）
Application Level Gateway (ALG) is application specific
translation agent that allows an application on a host in one
address realm to connect to its counterpart running on a host in
different realm transparently.
ARP
（
Address Resolution
Protocol
）
Internet protocol used to map an IP address to a MAC address.
A
AH
（
Authentication Header
）
A security protocol that provides data authentication and
optional anti-replay services. AH is embedded in the data to be
protected (a full IP datagram).
DDNS
（
Dynamic Domain
Name Server
）
The capability of assigning a fixed host and domain name to a
dynamic Internet IP address.
DHCP
（
Dynamic Host
Configuration Protocol
）
A protocol that automatically configure the TCP/IP parameters
for the all the PCs that are connected to a DHCP server.
DMZ
（
Demilitarized Zone
）
A Demilitarized Zone allows one local host to be exposed to the
Internet for a special-purpose service such as Internet gaming
or videoconferencing.
D
DNS
（
Domain Name
Server
）
An Internet Server that translates the names of websites into IP
addresses.
E
ESP
（
Encapsulating
Security Payload
）
Security protocol that provides data privacy services, optional
data authentication, and anti-replay services. ESP encapsulates
the data to be protected.
F
FTP
（
File Transfer
Protocol
）
Application protocol, part of the TCP/IP protocol stack, used for
transferring files between network nodes.
G
GMT
（
Greenwich Mean
Time
）
It is a term originally referring to mean solar time at the Royal
Observatory in Greenwich, London.
