스크립트 질문좀 드립니다

#!/bin/bash
 
SERVERS="1.1.1.1 2.2.2.1 3.3.3.1"
MON_INTV=10
MAX_RETRY=5
 
while true
do
        for server in $SERVERS
        do
                retry=0
                while [ $retry -lt $MAX_RETRY ]
                do
                        ping $server -c 1 -W 1 -q >/dev/null 2>&-
                        [ $? -eq 0 ] && break;
                        let retry++
                done
 
                [ $retry -eq $MAX_RETRY ] && echo "$server is down." || echo "$server is alive."
        done
 
        sleep $MON_INTV
done
 
exit 0;