Discuss The SecOps Group CNSP Exam Topic 10 Question 22

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

A53/TCP

B53/UDP

CBoth 1 and 2

DNone of the above

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.

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22 comments · newest first

Latonia 2 days ago

Wait, are you sure about that? Sounds off.

Lezlie 7 days ago

Both 1 and 2 make sense to me!

Avery 12 days ago

I thought it was just 53/UDP?

Kimbery 17 days ago

Definitely 53/TCP for zone transfers.

Diane 23 days ago

Nah, it’s only TCP that matters here.

Polly 28 days ago

Wait, both ports? That’s new to me!

Stefany 1 month ago

Both 1 and 2 is the right answer!

Rikki 1 month ago

I thought it was just 53/UDP?

Carylon 1 month ago

Definitely 53/TCP for zone transfers.

Lai 2 months ago

Yeah, I've seen zone transfers over TCP before.

Mee 2 months ago

Wait, are you sure about that? Sounds odd.

Amina 2 months ago

Both TCP and UDP are used, so C is correct.

Von 2 months ago

I thought it was only UDP!

Lavonna 2 months ago

Definitely 53/TCP for zone transfers.

Dyan 2 months 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.

Arlean 3 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.

Lorean 3 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?

Kattie 3 months ago

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

Latonia 3 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.

Aretha 3 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.

Ivan 4 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.

James 5 months ago

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

The SecOps Group CNSP Exam - Topic 10 Question 22 Discussion