Block URL iRule

For those interested, this is the best solution I found :

when DNS_REQUEST {

set lower [string tolower [DNS::question name]]
set q_name_label_split [split $lower "."]
set q_name_label [lindex $q_name_label_split end-1] 

if {[class match $q_name_label equals "URL_blocking"] }{
 log local0. "website blocked [DNS::question name] <$q_name_label> $q_name_label $lower"
 DNS::header rcode NXDOMAIN
 DNS::return
  }  
}

I split the request and get the domain to compare to my list