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Question

Difficulty: MediumNetworking Ports and Protocols

A network administrator is provisioning a new client VLAN on an enterprise network. Workstations on this subnet must automatically receive network configuration settings from a central server and resolve domain names to IP addresses. Which TWO port and protocol combinations must be permitted through the internal firewall to enable these two services? (Select TWO.)

  1. UDP port 53Answer
  2. UDP port 67Answer
  3. C
    TCP port 80
  4. D
    TCP port 443

Answer

The correct answers are UDP port 53 and UDP port 67.
UDP port 53 is used by DNS to resolve human-readable domain names into numerical IP addresses. UDP port 67 is used by DHCP servers to receive requests for automatic IP address assignment and configuration options. Together, allowing these two ports enables workstation IP boot configuration and hostname lookup capability.

Step-by-Step Solution

1
Identify the required network service for resolving domain names to IP addresses.
Domain Name System (DNS) handles hostname resolution and operates primarily on UDP port 53.
DNS query requests from clients to servers default to UDP port 53.
2
Identify the required network service for automatic IP address assignment.
Dynamic Host Configuration Protocol (DHCP) handles automatic IP leases and network parameter configuration, with the DHCP server receiving requests on UDP port 67.
Clients send broadcast requests to the DHCP server listening on UDP port 67 to receive network addresses.

Key Concept

DNS and DHCP Port Identification
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Topics

Networking Ports and Protocols

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