Certain considerations must be taken when using Linux kernel 2.4.x servers. If the server has a cluster address configured on the loopback device using the ip address add command, only one cluster address can be aliased.
ifconfig lo:num clusterAddress netmask 255.255.255.255 up
Additionally, there are incompatibilities between the ifconfig method of configuring interfaces and the ip method of configuring interfaces. Best practice suggests that a site choose one method and use that method exclusively.