User Guide

160 Glossary
Kerberos A secure network authentication system. Kerberos uses tickets, which are
issued for a specific user, service, and period of time. Once a user is authenticated, it’s
possible to access additional services without retyping a password (this is called single
sign-on) for services that have been configured to take Kerberos tickets. Mac OS X
Server uses Kerberos v5.
kernel The part of an operating system that handles memory management, resource
allocation, and other low-level services essential to the system.
key frame A sample in a sequence of temporally compressed samples that doesn’t rely
on other samples in the sequence for any of its information. Key frames are placed into
temporally compressed sequences at a frequency that’s determined by the key frame
rate.
L2TP Layer Two Tunnelling Protocol. A network transport protocol used for VPN
connections. It’s essentially a combination of Cisco’s L2F and PPTP. L2TP itself isn’t an
encryption protocol, so it uses IPSec for packet encryption.
LAN Local area network. A network maintained within a facility, as opposed to a WAN
(wide area network) that links geographically separated facilities.
LDAP Lightweight Directory Access Protocol. A standard client-server protocol for
accessing a directory domain.
managed network The items managed clients are allowed to “see” when they click the
Network icon in a Finder window. Administrators control this setting using Workgroup
Manager. Also called a “network view.”
metadata controller The computer that manages metadata in an Xsan storage area
network.
mutual authentication Also known as two-way authentication. A type of
authentication in which two parties authenticate with each other. For example, a client
or user verifies their identity to a server, and that server confirms its identity to the
client or user. Each side has the other’s authenticated identity.
NAT Network Address Translation. A method of connecting multiple computers to the
Internet (or any other IP network) using one IP address. NAT converts the IP addresses
you assign to computers on your private, internal network into one legitimate IP
address for Internet communications.
NetBoot server A Mac OS X server on which you’ve installed NetBoot software and
have configured to allow clients to start up from disk images on the server.
Network File System See NFS.
network view See managed network.