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Difficulty: EasyDNS Lookup and Name Resolution Roles in Enterprise Networks

A network administrator is verifying traffic flows from client workstations in an enterprise environment. Which transport layer protocol and destination port does a host client use by default when submitting standard domain name lookup queries to a DNS server?

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

Answer

Standard DNS lookup queries sent by host clients use UDP port 53.
Standard DNS lookup requests from client endpoints rely on UDP port 53 to achieve fast, low-latency name resolution without needing a three-way TCP handshake.

Step-by-Step Solution

1
Identify the application protocol responsible for resolving hostnames into IP addresses.
The Domain Name System (DNS) performs name-to-IP resolution.
Host clients require an IP address to encapsulate data packets destined for named network resources.
2
Determine the transport protocol and port used for standard client queries.
Standard DNS queries use User Datagram Protocol (UDP) on destination port 53.
UDP provides fast, connectionless transmission without connection establishment overhead, making it ideal for quick query-and-response transactions.

Key Concept

DNS Transport Layer Mechanics (UDP Port 53)
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Topics

DNS Lookup and Name Resolution Roles in Enterprise Networks

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