問72
頻出度★★★
プライベートIPアドレスに関する記述として，適切なものはどれか。
平成28年度 秋期 ITパスポート試験 問72
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 72
Incorrectア
What ICANN (and IANA and the regional registries under it) manages and assigns so as to be globally unique is the global IP address. Private IP addresses have their assignment ranges defined by a standard and can be used freely within an organization, so they are not assigned by ICANN.
Incorrectイ
A private IP address can be assigned not only to PCs and routers but also to servers used within a company. Whether it can be assigned is determined not by “whether it is accessed by many users” but by whether the device is used within a closed network, so this statement is incorrect.
- ウ
正解 A private IP address is an address that is valid only within a closed network, such as inside a company, and cannot communicate with a party on the Internet as is. Therefore, a router or similar device at the boundary between the internal company network and the Internet uses the NAT (Network Address Translation) function to convert the terminal’s private IP address into a global IP address that is valid on the Internet. This makes it possible even for a terminal with a private IP address to access the external Internet. Therefore “ウ” is correct.
Incorrectエ
A private IP address is an address that can be used freely within an organization, and there is no need to apply to or receive approval from a provider (ISP). What requires application and assignment is the global IP address, which is uniquely valid on the Internet.
ここがポイント
- Grasp the difference in roles: a private IP address is valid only within a closed network such as inside an organization and can be used freely, whereas a global IP address is managed and assigned so as to be globally unique under ICANN/IANA.
- NAT (Network Address Translation) is a function that mutually converts private IP addresses and global IP addresses, serving as a bridge when an internal company terminal accesses the external Internet.
用語