問75
頻出度★★★
PCに設定する IPv4の IP アドレスの表記の例として, 適切なものはどれか。
令和2年度 ITパスポート試験 問75
テクノロジ系ネットワーク › ネットワーク応用
This question's explanation and your answers so far.
解説
問 75
Incorrectア
“00.00.11.aa.bb.cc” has six groups of values and even contains hexadecimal (letter) parts such as “aa,” “bb,” and “cc.” This does not match the IPv4 format of four decimal octets. It is instead closer to a MAC address, which consists of six groups of hexadecimal digits, and is not an IPv4 address notation.
Incorrectイ
“050-1234-5678” is separated by hyphens rather than periods, and is divided into only three groups. This is a notation like a telephone number, not the IPv4 address format that separates four octets with periods.
- ウ
正解 The standard way to write an IPv4 address is to divide the 32-bit value into four 8-bit groups (octets), express each octet as a decimal number from 0 to 255, and join them with periods — the “dotted-decimal notation.” In choice “ウ,” “10.123.45.67,” all four numbers fall within the 0–255 range and are separated by periods, so it exactly matches this format. Therefore “ウ” is an appropriate example of how an IPv4 address configured on a PC is written.
Incorrectエ
“http://www.example.co.jp/” is a URL that indicates the location of a web page (an address containing a domain name), not an IP address itself. A domain name is ultimately converted into an IP address by DNS, but the notation itself is not in the IPv4 address format (four decimal octets).
ここがポイント
- An IPv4 address is written in “dotted-decimal notation”: the 32 bits are divided into four octets of 8 bits each, each octet is expressed as a decimal number from 0 to 255, and they are joined with periods.
- Distinguishing from similar formats: six groups of hexadecimal digits form a MAC address, hyphen-separated notation is a telephone number, and something beginning with http:// is a URL — none of these are IPv4 address notations.
用語