200-301 Question #842: Real Exam Question with Answer & Explanation

Question

Which two statements about DNS lookup operations are true? (Choose two.)

Options

• AWhen the primary IP address of the destination is down, the DNS server can forward the client to
• BThe client sends a request for IP address to domain name resolution to the DNS server.
• CThe DNS server pings the destination to verify that is available.
• DThey use destination port 53.
• EThe client sends a request for domain name to IP address resolution to the DNS server.

Explanation

DNS lookup operations primarily involve clients requesting resolution of domain names to IP addresses, and these requests utilize destination port 53.

Common mistakes.

• A. DNS servers are responsible for name-to-IP resolution, not for determining the liveness of a destination IP address or redirecting clients based on network reachability.
• B. While reverse DNS lookups (IP to domain name) are possible, the primary and most common client request to a DNS server is for domain name to IP address resolution.
• C. DNS servers do not perform ICMP pings to verify the availability of destination hosts; their function is strictly name resolution.

Concept tested. DNS lookup fundamentals (ports, query types)

Reference. https://learn.microsoft.com/en-us/windows-server/networking/dns/what-is-dns

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