In IPv4, which header field controls the maximum hops and can aid topology discovery?

Study for the SANS560 GIAC Penetration Tester (GPEN) Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Multiple Choice

In IPv4, which header field controls the maximum hops and can aid topology discovery?

Explanation:
Time to Live is the header field that sets how many routers a packet can traverse before being dropped. It’s decremented by every router along the path, and if it reaches zero, the router discards the packet and usually sends back an ICMP Time Exceeded message. This mechanism is what enables topology discovery tools like traceroute to map the route: by sending packets with increasing TTL values, each router along the path replies, revealing the hop-by-hop path to the destination. The field is 8 bits wide, allowing a practical range up to 255 hops. The other options don’t control hop count or aid topology discovery in the same way: Protocol indicates the upper-layer protocol, Destination IP is the target address, and Checksum protects header integrity.

Time to Live is the header field that sets how many routers a packet can traverse before being dropped. It’s decremented by every router along the path, and if it reaches zero, the router discards the packet and usually sends back an ICMP Time Exceeded message. This mechanism is what enables topology discovery tools like traceroute to map the route: by sending packets with increasing TTL values, each router along the path replies, revealing the hop-by-hop path to the destination. The field is 8 bits wide, allowing a practical range up to 255 hops. The other options don’t control hop count or aid topology discovery in the same way: Protocol indicates the upper-layer protocol, Destination IP is the target address, and Checksum protects header integrity.

More Multiple Choice Questions
Subscribe

Get the latest from Passetra

You can unsubscribe at any time. Read our privacy policy