問61
頻出度★★★
最大32文字までの英数字が設定でき, 複数のアクセスポイントを設置したネットワークに対しても使用できる, 無線LANのネットワークを識別するものはどれか。
平成23年度 特別試験 ITパスポート試験 問61
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 61
- ア
正解 The correct answer is “ア ESSID”. An ESSID (Extended Service Set Identifier) is the name given to a wireless LAN network (a network identifier), and it can be set freely with up to 32 alphanumeric characters. It is an extension of the SSID, which originally identified one access point together with the terminals under it as a single unit (a BSS); if you set the same ESSID on several access points, they can be handled together as one wireless LAN network (an ESS). Because of this, even when a user moves around a large office or floor and the access point switches over (roaming), the user can stay connected to the same network name. ESSID is the only choice that satisfies all three conditions in the question: up to 32 alphanumeric characters, usable even with multiple access points, and identifying a wireless LAN network.
Incorrectイ
An IP address is a logical address used on a TCP/IP network to identify the device (host) you are communicating with, and it is used on both wired and wireless networks. What it identifies is not the name of a network but each individual device (and the network number it belongs to), and its value is not 32 alphanumeric characters but a numeric notation (32 bits for IPv4). On both of these points it does not match the conditions in the question.
Incorrectウ
A MAC address is a unique 48-bit physical address assigned to a NIC (network interface) when it is manufactured, and it identifies each individual device. It is not something a user can set as any 32 alphanumeric characters, nor is it a name given to a whole wireless LAN network, so it is wrong.
Incorrectエ
RFID is a technology that uses radio waves to read and write data between a tiny IC tag and a reader/writer, so that objects or people are identified automatically. It is used for things such as transit IC cards, product tags, and entry/exit management, and has nothing to do with a mechanism for identifying a wireless LAN network.
ここがポイント
- ESSID (SSID) = the network identifier of a wireless LAN. It can be set with up to 32 alphanumeric characters, and setting the same value on several access points groups them into a single network (an ESS), which makes roaming possible.
- Distinguish between what identifies a network and what identifies a device. A MAC address is a physical address unique to a device (interface), and an IP address is a logical address used for communication; neither of them is the name of a network.
用語