フリー問題

問題文

Two kinds of information are consistently missing from every capture the team takes, no matter which laptop is used. One kind carries no upper-layer content at all. The other kind sits in front of every single transmission. Which pairing names them?

選択肢

1. Content-free frames vanish because the adapter drops the null packet, and the bits ahead of every frame vanish because the radio consumes the duplicate header that instrumentation cannot recover.
2. Content-free frames vanish because the adapter drops the tagged packet, and the bits ahead of every frame vanish because the radio consumes the preamble header that instrumentation cannot recover.
3. Content-free frames vanish because the adapter drops the tagged packet, and the bits ahead of every frame vanish because the radio consumes the duplicate header that instrumentation cannot recover.
4. Content-free frames vanish because the adapter drops the null packet, and the bits ahead of every frame vanish because the radio consumes the preamble header that instrumentation cannot recover.