A

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Address Resolution Protocol (ARP)

A protocol that maps an IP address to the hardware address on a network card.

anacron

The anacron service, while not included with RHEL 3, is part of the RHCT prep course as of this writing (and is therefore required knowledge for RHCEs). It runs cron jobs that could not run while a server was powered down.

Apache Web server

The Apache Web server provides both normal and secure Web services. Apache is controlled by the httpd daemon.

apachectl

The apachectl command is the preferred method to start and stop an Apache server.

arp (Address Resolution Protocol) command

The arp command is used to view or modify the kernel's ARP table. Using arp, you can detect problems such as duplicate addresses on the network. Alternatively, you can use arp to add the required entries from your LAN.

at

The at command is similar to cron, but it allows you to run a job on a one-time basis.

authentication

The way Linux checks the login rights of a user. Linux and Unix users are normally authenticated through use of a username and password, checked against /etc/passwd and related files.

Automounter

The Automounter can be configured to mount local and network directories on an as-needed basis. It's configured in /etc/auto.master and /etc/auto.misc.

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