問題文
A firewall bridges two segments. Which statement describes how it builds the table it uses to pick an egress port, and what it does with a destination that is absent from that table?
選択肢
- The table is filled in by an operator who enters the address of every host attached to the segment, and a destination absent from the table is discarded with a report sent back to the sender
- The table is filled in by watching the source address of arriving frames against the port they arrived on, and a destination absent from the table is sent out of every other port
- The table is filled in by asking the upstream router for its own table, and a destination absent from the table is sent to that router as a default
- The table is filled in by a protocol that the two firewalls run between themselves, and a destination absent from the table is queued until that protocol converges