平成27年度秋期 ITパスポート試験問67

This question's explanation and your answers so far.

問67

頻出度★★★

NAT (Network Address Translation) がもつ機能として, 適切なものはどれか。

出典　平成27年度秋期 ITパスポート試験問67

解説

問 67

Incorrectア
Mapping an IP address to a MAC address is the role of ARP (Address Resolution Protocol), not a function of NAT.
Incorrectイ
Finding a host name from an IP address (reverse lookup) is a function of DNS; NAT only converts the type of address and has nothing to do with host names.
Incorrectウ
Converting a host name into an IP address (forward lookup) is the role of DNS (Domain Name System), not a function of NAT.
エ
正解 NAT (Network Address Translation) is a function that maps (converts) between the private IP addresses used within an internal LAN, such as a company network, and the global IP addresses used on the Internet side. A private IP address cannot reach the Internet on its own, so a device such as a router uses NAT to replace it with a global IP address, letting internal devices communicate with the outside. Therefore choice エ, which maps a private IP address to a global IP address, is correct.

ここがポイント

NAT maps private IP addresses to global IP addresses, letting devices on an internal network communicate with the Internet.
Distinguishing easily confused functions: converting between host names and IP addresses is handled by DNS, while resolving an IP address to a MAC address is handled by ARP.

用語

解答問67エ