IPA IP 2024 Question 100

Topic: Security

A question IPA Japan published in 令和6年度 ITパスポート試験 公開問題 問100, translated into English. ITPEC is based on the same exams.

Same question on ITPEC: Apr 2026 Q45

A user who specifies a correct URL and attempts to access the website on the Internet is connected to a fake website. When the cause was investigated, it was found that there was a vulnerability on the server that matches a domain name with an IP address, and the information on the server was overwritten by an attacker. Which of the following is the attack against this server?

Explanation

DNS cache poisoning — the attacker overwrote the DNS server's name-to-address records, so a correct URL led to a fake site.

The server that matches a domain name with an IP address is a DNS server. A caching DNS server keeps the answers it receives so it can reply to later queries directly. In cache poisoning the attacker exploits a vulnerability to plant a forged record, mapping the genuine domain name to the attacker's IP address. Every user of that DNS server who types the correct URL is then sent to the fake site until the entry is removed or expires.

Answer (b)

Why not others:

  • •(a) DDoS attack — floods a target from many machines to stop its service; it overloads the server rather than rewriting its data
  • •(c) Social engineering — tricks people, for example by phone or by peeking, into revealing information; it does not exploit a server vulnerability
  • •(d) Drive by download — makes a browser download malware just by visiting a compromised page; it attacks the visitor's PC, not the name resolution

Key rule: A correct URL that reaches the wrong site points at name resolution: the DNS records (or the PC's hosts file) have been falsified; DNSSEC signatures protect against forged DNS answers.

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This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.