CentOS install

Close ALL port forwards in the firewall  to the server IP we are about to install
Install CentOS from DVD by booting from it.  Set system time to UTC.
Partition /dev/sda1 as “boot” 100Meg ext3
Partition /dev/sda2 as “/ “ 2000Meg ext3 minimum.  No problem using more if you have more
Partition /dev/sda3 as "swap" (optional, not recommended if using flash drive) make the size equivalent to twice the amount of RAM 
Set static IP, netmask, gateway, DNS server
Set hostname to something like "asterisk.local".  If you have multiple installs it is important to make this hostname unique for each install so when you get email notifications you will know which PBX is sending it.

If you have 2 ethernet ports make eth0 and eth1 identical except eth0 is active on boot and eth1 is NOT!  That way if eth0 ever fails you can easily switch over the cable and activate eth1.

Ensure that all package groups and modules in default and custom install packages are DE-selected for install (including "base system") so that only a bare minimal install is done:

For performance and security reasons it is important to update the system immediately after install.
yum -y update

The following packages also need to be installed with yum:

yum install ncurses-devel tftp-server libtermcap-devel nano ntp wget setuptool gcc gcc-c++ make flex patch bison kernel-devel byacc sendmail cpuspeed system-config-network-tui acpid subversion

Disable Firewall and SELinux
setup agent

Go to firewall configuration and ensure SELinux and Firewall are disabled