Irule with Multiple URL's

Modified to use your four specified FQDNs:

when RULE_INIT {
 set ::whichone 0
} 

when HTTP_REQUEST { 
 switch $::whichone { 
  0 { HTTP::redirect "http://www.abc.com” }
  1 { HTTP::redirect "http://www.aaa.com” } 
  2 { HTTP::redirect "http://www.bbb.com” }
  3 { HTTP::redirect "http://www.ccc.com” }
  }
 set ::whichone [expr ! $::whichone]
}