CCNA Network Services and Security Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Client sends DNS query to local resolver; server responds with A-record; client uses IP address; then nslookup for basic query; then dig for detailed diagnostics.

  Why this is correct

  The sequence is technically sound: the client first sends a recursive query to its configured local resolver, which iteratively walks the DNS hierarchy if needed and returns an A record mapping the hostname to an IPv4 address. Only after receiving that answer does the client actually use the IP for its TCP/UDP session. For post-resolution troubleshooting, nslookup is the lightweight, universally available query tool that checks the resolution path, while dig provides extended output (query time, TTL, authority section, EDNS, DNSSEC flags) needed for deeper diagnosis. Thus the order reflects both the protocol's dependency flow and the appropriate escalation of diagnostic tools.

• ✗

  Client sends DNS query to local resolver; server responds with A-record; client uses IP address; then dig for detailed diagnostics; then nslookup for basic query.

  Why it's wrong here

  Placing dig before nslookup inverts the conventional troubleshooting ladder. After the host already holds the A record and is using the IP, an administrator typically runs nslookup first because it is a simple, interactive DNS lookup utility that confirms whether the resolver returns the expected record. dig is a more powerful diagnostic utility that should come later because it exposes detailed response metrics and lower-level DNS internals; using it first is not inherently harmful, but it skips the quick baseline check and therefore violates the described workflow's efficiency.

• ✗

  Client sends DNS query to local resolver; client uses IP address; server responds with A-record; then nslookup for basic query; then dig for detailed diagnostics.

  Why it's wrong here

  This sequence breaks the causal dependency in DNS resolution: the client cannot use the IP address until the resolver's response has been received and parsed. The A record is the answer that supplies the numbered IPv4 destination; initiating the connection before receiving that answer is impossible at Layer 3/4. Additionally, the troubleshooting utilities, nslookup and dig, only appear after the use of the IP in this choice, but the underlying error is the impossible ordering at the front of the chain. Correctly, the server response must precede any use of the address.

• ✗

  Client sends DNS query to local resolver; server responds with A-record; then nslookup for basic query; then dig for detailed diagnostics; then client uses IP address.

  Why it's wrong here

  This option defers the client's actual use of the IP address until after both diagnostic commands have been run, which is functionally backwards. In the real flow, the application's connection to the resolved IP is the immediate consequence of receiving the A record—the operating system hands the address to the protocol stack for the TCP handshake. nslookup and dig are out-of-band troubleshooting utilities that query DNS independently; they do not supply the IP to the connecting process. Therefore, placing them before the client 'uses IP address' is unrealistic and misrepresents when the address becomes available.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”