Which of the following ports should be allowed through a firewall to allow DNS resolution to occur to an outside DNS server?

The correct answer is B. 53. DNS (Domain Name System) uses port 53 for both UDP (standard queries) and TCP (zone transfers and large responses). To allow clients to resolve domain names via an external DNS server, port 53 must be open on the firewall. Port 20 is FTP data, port 80 is HTTP, and port 3389 is…

Network security

Question

Options

A20
B53
C80
D3389

How the community answered

(47 responses)

A
9% (4)
B
87% (41)
C
2% (1)
D
2% (1)

Explanation

DNS (Domain Name System) uses port 53 for both UDP (standard queries) and TCP (zone transfers and large responses). To allow clients to resolve domain names via an external DNS server, port 53 must be open on the firewall. Port 20 is FTP data, port 80 is HTTP, and port 3389 is RDP.

Topics

#DNS#port 53#firewall rules#name resolution

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