RCHE Red Hat Certified Engineer Linux Study Guide[c] Exam (Rh302)

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.