The SecOps Group CNSP Exam - Topic 1 Question 16 Discussion

Actual exam question for The SecOps Group's CNSP exam

Question #: 16
Topic #: 1

[All CNSP Questions]

What ports can be queried to perform a DNS zone transfer?

A53/TCP

B53/UDP

CBoth 1 and 2

DNone of the above

Show Suggested Answer

Suggested Answer: A

A DNS zone transfer involves replicating the DNS zone data (e.g., all records for a domain) from a primary to a secondary DNS server, requiring a reliable transport mechanism.

Why A is correct: DNS zone transfers use TCP port 53 because TCP ensures reliable, ordered delivery of data, which is critical for transferring large zone files. CNSP notes that TCP is the standard protocol for zone transfers (e.g., AXFR requests), as specified in RFC 5936.

Why other options are incorrect:

B . 53/UDP: UDP port 53 is used for standard DNS queries and responses due to its speed and lower overhead, but it is not suitable for zone transfers, which require reliability over speed.

C . Both 1 and 2: This is incorrect because zone transfers are exclusively TCP-based, not UDP-based.

D . None of the above: Incorrect, as 53/TCP is the correct port for DNS zone transfers.

by Tijuana at Nov 25, 2025, 12:11 AM

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Tom

12 hours ago

Wait, are you sure about that?

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Mitsue

6 days ago

Both 1 and 2 make sense to me!

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Craig

11 days ago

I thought it was just 53/UDP?

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Daniela

16 days ago

Definitely 53/TCP for zone transfers.

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Pansy

21 days ago

I wonder if the correct answer is "All of the above, plus 80/TCP for good measure."

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Lajuana

26 days ago

I bet the person who wrote this question is a DNS expert. Or maybe just a sadist.

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Ruthann

1 month ago

D) None of the above? Really? That's a trick question if I ever saw one.

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Judy

1 month ago

I always get confused between TCP and UDP. Maybe I should just memorize the ports instead.

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Gerald

1 month ago

I feel like I’ve seen questions where both ports were relevant, so I might go with C, but I need to double-check my notes.

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Alyssa

2 months ago

I’m a bit confused here. I thought zone transfers were only over TCP, but I could be mixing it up with something else.

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Laquita

2 months ago

This is a good one. I remember learning about DNS zone transfers in class. I'm confident the answer is C - both TCP and UDP port 53 can be used.

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Lajuana

2 months ago

Ugh, I hate DNS questions. There are so many little details to remember. I'm just going to take my best guess and hope for the best on this one.

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Arminda

2 months ago

C) Both 1 and 2 is the correct answer.

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Ollie

2 months ago

Okay, let me see here. DNS zone transfers are a bit tricky, but I'm pretty sure the standard ports are 53/TCP and 53/UDP. I'll double-check my notes to be sure.

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Elliot

2 months ago

I think zone transfers typically use TCP, so I’m leaning towards A, but I’m not completely sure.

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Tora

3 months ago

I remember practicing a question about DNS and ports, and I think both TCP and UDP were mentioned. Maybe it’s C?

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Anglea

3 months ago

Hmm, I'm not totally sure about this one. I know DNS uses port 53, but I'm not certain if that applies to zone transfers specifically. I'll have to think it through carefully.

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Oliva

3 months ago

I think I know the answer to this one. It's definitely C - both 53/TCP and 53/UDP can be used for DNS zone transfers.

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Chaya

3 months ago

C it is! Nice job on that!

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