Today when I was doing tracert, in the 6th Hop I get RTO but my next hop seems to be reachable. How come it works?
6 * * * Request Timed Out 7 58ms 58ms 61ms 18.104.22.168
As per my knowledge:
Tracert will initiate ICMP echo request for 1st hop with TTL=1 with 3 packets.
When it reaches a router(1), the TTL becomes 0 and Time Exceeded Message is sent to the Source by the router(1).
Now source will set TTL=2 and sends it again. Now router(1) will decrement TTL to 1 and sends it to the next router(2).
Router(2) will send Time Exceeded Message to the source as TTL expires. Likewise Source increments TTL value and sends it towards destination.
If my 6th Hop gets RTO, the router is down or firewall blocking and hence it won't send ICMP reply to the source. Then, how come the source knows that next router is alive, without getting ICMP reply from the previous router, how source finds the next hop or router?