Query regarding commit

General questions
1

Hi team,

Wanted to know the working of commit , when we configure any firewall rules i believe the same gets added to some temporary config to be written to linux iptables on commit here does the exisitng iptables rules gets flushed and all the rules are written again to iptables along with the updated rules or only the new rules are updated to iptables.

Regards

2

I guess only changes are done. Which can be verified by looking at rule counters,
In flush case, rule counters will zero out after some change