フリー問題

問題文

A school still has a handful of old barcode scanners which support only the 802.11b physical layer. An administrator needs to know what those devices can and cannot do on the network. Which description is accurate?

選択肢

1. They use OFDM in the 2.4 GHz band and reach 11 Mbps at most on any 20 MHz channel in the school.
2. They use OFDM in the 5 GHz band and top out at 54 Mbps on a 20 MHz channel with no access at all to the 2.4 GHz band today.
3. They use HR-DSSS in both of the bands and reach 54 Mbps whenever the channel is clear of other traffic on the floor.
4. They use HR-DSSS in the 2.4 GHz band and top out at 11 Mbps with no access at all to the 5 GHz band.