Which command tests MTU issues on jumbo networks by attempting a destination path with a large payload?

Which command tests MTU issues on jumbo networks by attempting a destination path with a large payload?

• A. ping -M do -s 8972 <host>
• B. ping -M do -s 1472 <host>
• C. traceroute <host>
• D. dig <host>

Answer: (A)

Testing path MTU on jumbo networks means trying to push a packet size large enough to require a jumbo frame, while ensuring no fragmentation occurs. The command that does this uses a non-fragmenting ping with a payload large enough to create a 9000-byte IP packet. The option -M do disables fragmentation, and -s 8972 sets the ICMP payload so that, together with the 20-byte IP header and 8-byte ICMP header, the total becomes 9000 bytes. If the path cannot handle a jumbo MTU, this packet will fail, revealing MTU issues. The other options don’t target jumbo MTU in the same way: a payload of 1472 bytes would yield a total size of 1500 bytes (standard MTU), so it won’t test jumbo capabilities. Traceroute checks route awareness and hop-by-hop timing, not MTU handling. Dig is a DNS query tool and has no MTU testing function.

Testing path MTU on jumbo networks means trying to push a packet size large enough to require a jumbo frame, while ensuring no fragmentation occurs. The command that does this uses a non-fragmenting ping with a payload large enough to create a 9000-byte IP packet. The option -M do disables fragmentation, and -s 8972 sets the ICMP payload so that, together with the 20-byte IP header and 8-byte ICMP header, the total becomes 9000 bytes. If the path cannot handle a jumbo MTU, this packet will fail, revealing MTU issues.

The other options don’t target jumbo MTU in the same way: a payload of 1472 bytes would yield a total size of 1500 bytes (standard MTU), so it won’t test jumbo capabilities. Traceroute checks route awareness and hop-by-hop timing, not MTU handling. Dig is a DNS query tool and has no MTU testing function.