ICND2 – IP Routing 2
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Question 1
[am4show have=’p2;’]Refer to the exhibit, Host A pings interface S0/0 on router 3, what is the TTL value for that ping?
A. 253
B. 252
C. 255
D. 254
Answer: A[/am4show]
Explanation
From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL.
The picture below shows TTL values for each interface of each router and for Host B. Notice that Host A initializes ICMP packet with a TTL of 255: