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The SecOps Group CNSP Exam - Topic 10 Question 22 Discussion

What ports can be queried to perform a DNS zone transfer?
A) 53/TCP
B) 53/UDP
C) Both 1 and 2
D) None of the above

The SecOps Group CNSP Exam - Topic 10 Question 22 Discussion

Actual exam question for The SecOps Group's CNSP exam
Question #: 22
Topic #: 10
[All CNSP Questions]

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

Show Suggested Answer Hide 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 Xuan at May 13, 2026, 03:41 AM

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Stefany
3 days ago
Both 1 and 2 is the right answer!
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Rikki
8 days ago
I thought it was just 53/UDP?
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Carylon
13 days ago
Definitely 53/TCP for zone transfers.
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Lai
18 days ago
Yeah, I've seen zone transfers over TCP before.
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Mee
24 days ago
Wait, are you sure about that? Sounds odd.
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Amina
29 days ago
Both TCP and UDP are used, so C is correct.
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Von
1 month ago
I thought it was only UDP!
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Lavonna
1 month ago
Definitely 53/TCP for zone transfers.
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Dyan
1 month ago
I’m a bit confused here. I thought zone transfers were only over TCP, but I guess I should double-check if UDP plays a role too.
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Arlean
2 months ago
I practiced a similar question where it mentioned that zone transfers are usually done over TCP. So I’d probably go with A, but I could be wrong.
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Lorean
2 months ago
I remember reading that both TCP and UDP can be involved in DNS, but zone transfers specifically might only use TCP. So maybe it’s A?
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Kattie
2 months ago
I think zone transfers typically use TCP, so I’m leaning towards A. But I’m not completely sure about UDP.
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Latonia
2 months ago
I’m confused about this one. I thought zone transfers were only on TCP, but I guess I should double-check if UDP plays a role as well.
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Aretha
2 months ago
I’m pretty certain that port 53/TCP is the main one for zone transfers, but I feel like I’ve seen questions that mention UDP too.
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Ivan
3 months ago
I remember practicing a question about DNS that mentioned both TCP and UDP, but I can’t recall if both are used for zone transfers.
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James
4 months ago
I think zone transfers typically use TCP, so I’m leaning towards A. But I’m not completely sure about UDP.
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