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Two-Minute Drill
Here are some of the key points from the certification objectives in Chapter 9.
DNS/BIND
DNS, the Domain Name System, includes a database of computer names and IP addresses.
DNS is based on the Berkeley Internet Name Domain (BIND), using the named daemon.
Critical DNS configuration files include /etc/named.conf and the files in the /var/named directory.
Caching-only DNS servers store requests and their associated IP addresses on a computer.
Every time you change DNS, remember to update the serial number in your zone file. Otherwise, other DNS servers don't realize that you've changed anything.
Network File System (NFS)
NFS is the standard for sharing files and printers between Linux and Unix computers.
Key NFS processes are rpc.mountd for mount requests, rpc.rquotad for quota requests and nfsd for each network share.
NFS shares are configured in /etc/exports and activated with the exportfs -a command.
Clients can make permanent connections for NFS shares through /etc/fstab.
If an NFS server fails, it can 'hang' an NFS client. When possible, avoid using NFS on mission-critical computers.
NFS and portmap have security problems. Limit their use when possible to secure internal networks protected by an appropriate firewall.
DHCP
DHCP (Dynamic Host Configuration Protocol) allows a client computer to obtain network information (such as an IP number) from a server.
The bootp protocol allows a client computer to access a DHCP server on a remote network.
DHCP servers are configured through /etc/dhcpd.conf.
Remember that the DHCP server daemon is dhcpd; the DHCP client daemon is dhclient.
Keeping Servers in Sync
You can keep the time on a server in sync with UTC using the Network Time Protocol (NTP).
The configuration file for NTP is /etc/ntp.conf.
The Red Hat Date/Time Configuration tool is a GUI utility that can help you configure /etc/ntp.conf.
