Blocking ip on cluster server

How to optimize .htaccess file

[FromBelgium]

I use cluster server and below is only option to Block IP's.
Is there a way to make the very long file shorter?
How can I block an IP range with this method?

SetEnvIf X-Cluster-Client-Ip 11.1.11.111 block
SetEnvIf X-Cluster-Client-Ip 11.1.11.112 block
SetEnvIf X-Cluster-Client-Ip 11.1.11.113 block
SetEnvIf X-Cluster-Client-Ip 11.1.11.114 block
SetEnvIf X-Cluster-Client-Ip 11.1.11.115 block
SetEnvIf X-Cluster-Client-Ip 11.1.11.116 block
'
'
Deny from env=Block

[wilderness]

I don't have a clue what cluster server is!

#SHOULD deny 11.1.11.0-2555
SetEnvIf X-Cluster-Client-Ip 11.1.11. block

[jdMorgan]

SetEnvIf uses regular expressions, so

SetEnvIf X-Cluster-Client-Ip ^11\.1\.11\.11[1-6]$ block

replaces all six lines, as well as correcting the unanchored pattern and un-escaped literal periods.

This assumes that the X-Cluster-Client-Ip variable is defined within the scope where this SetEnvIf directive executes.

Jim