Which IPv4 issue concerns routing tables becoming unwieldy?

• A. Fragment reassembly overhead
• B. Routing table sizes are unwieldy
• C. Overhead due to IP options
• D. IPv6 header length

Answer: (B)

The idea being tested is how the routing table in IPv4 scales as networks grow. Each distinct network prefix that an IPv4 router must reach needs an entry in the routing table. As more networks appear, the number of entries increases, demanding more memory and making lookups slower. That buildup can make the routing table unwieldy, impacting router performance and manageability. This is a fundamental concern because it directly ties to how efficiently a network can route packets.

The other options describe different IPv4 issues that don’t center on the size or manageability of the routing table itself: fragment reassembly overhead is about reconstructing large IP fragments, not about how many routes exist; overhead due to IP options refers to extra processing per packet from options fields; and IPv6 header length concerns a different protocol version altogether, not the IPv4 routing table growth.