令和7年度 ITパスポート試験 問58

※ Our check while writing this explanation could not fully confirm the published answer; scoring follows IPA's official key.

• ×Incorrectア

  A protocol that automatically assigns information such as IP addresses to computers attempting to connect to an IP network describes DHCP (Dynamic Host Configuration Protocol), not DNS.

• ×Incorrectイ

  Encrypting communication between a browser and a web server to improve security describes HTTPS (SSL/TLS), which has a different role from DNS, which performs name resolution.

• ○ウ

  正解 DNS (Domain Name System) is a mechanism that maps host names or domain names that are easy for people to use (e.g., www.example.com) to the IP addresses that devices use for communication (e.g., 203.0.113.10). This lets users access the target server by domain name without having to remember numeric IP addresses, and the name resolution is handled by DNS servers on the network. Therefore, choice ウ, which states that it is “a mechanism that maps host names or domain names to IP addresses,” is correct.

• ×Incorrectエ

  DNS maps to IP addresses, not MAC addresses. Mapping IP addresses to MAC addresses is the role of ARP, so the mapping target in this choice is incorrect.