Ubuntu :: Connection Monitor Script Works Incorrect?

My promlem is that i wrote a few simple script to monitor the network connection as follows:
script 1 "netmonitor.sh"

Quote:
#!/bin/bash
# /usr/local/bin/netmonitor.sh
ping -c 1 "$HOST" > /dev/null 2>&1
if [ $? = 0 ]; then
echo "`date` Network is ready!" |

[Code]...

Is it possible, that if system don't use the connection after getting the DHCP lease, it close the connection automaticly? Anyway it works ok, but i don't want to owerwrite my router's flash in every 5 seconds with te new lease, my script probably defeat it soon if i don't do anything