Select server with bash case based on IP subnet

1. !/bin/bash

server_ip=hostname -I | cut -d' ' -f1

case "$server_ip" in

   10.5.15.*)
   backup_ip=10.5.15.242
   ;;
   10.8.15.*)
   backup_ip=10.8.15.242
   ;;

10.5.12.*)

   backup_ip=10.5.12.142
   ;;

esac

echo "$backup_ip"