問88
頻出度★★★
無線LAN に関する記述のうち, 適切なものだけを全て挙げたものはどれか。 a 使用する暗号化技術によって, 伝送速度が決まる。 b 他の無線LANとの干渉が起こると, 伝送速度が低下したり通信が不安定になったりする。 c 無線LANで TCP/IP の通信を行う場合, IP アドレスの代わりに ESSID が使われる。
令和2年度 ITパスポート試験 問88
テクノロジ系ネットワーク › ネットワーク方式
This question's explanation and your answers so far.
解説
問 88
Incorrectア
“a, b”. b is correct, but a is wrong. What determines the transmission speed of a wireless LAN is a communication standard such as IEEE 802.11a/b/g/n/ac (modulation scheme, frequency band, channel width, etc.), not an encryption technology such as WPA2. Encryption protects the content of communication and does not define the speed itself (the load of encryption processing may lower it slightly, but that does not mean it “determines the speed”). This option, which includes a, is inappropriate.
- イ
正解 Only statement b is appropriate, so “イ”, which lists only b, is correct. In a wireless LAN, multiple devices share radio waves in the same frequency band (such as the 2.4 GHz band), so when nearby devices use the same band, such as another wireless LAN or a microwave oven, radio interference occurs. When interference happens, retransmissions increase and the effective transmission speed drops, or communication is interrupted and becomes unstable. This is a basic property of wireless communication, so statement b is correct.
Incorrectウ
“b, c”. b is correct, but c is wrong. An ESSID (SSID) is a name that identifies a wireless LAN access point (network) and is used to choose which network to connect to. In TCP/IP communication, the other party is still specified by an IP address as usual, so an ESSID never replaces an IP address. This option, which includes c, is inappropriate.
Incorrectエ
“c”. This option treats only c as appropriate, but c is wrong and b is correct. An ESSID does not replace an IP address; the correct statement is b, about interference. Therefore this option, which lists c, is inappropriate.
ここがポイント
- What determines the transmission speed of a wireless LAN is an IEEE 802.11 family communication standard, not an encryption technology (such as WPA2) or an ESSID.
- An ESSID (SSID) is a name that identifies a wireless network; it does not replace the IP address in TCP/IP. When radio interference occurs, it causes speed degradation and unstable communication.
用語