An enterprise workstation attempts to connect to an external service by domain name (web.example.com) for the first time. Arrange the following DNS lookup and name resolution steps in the correct sequential order from the client's initial request to receiving the final IP address.
- 1The workstation checks its local operating system DNS resolver cache and local hosts file.
- 2The workstation transmits a recursive DNS query to its configured local enterprise DNS resolver over UDP port 53.
- 3The enterprise DNS resolver sends an iterative query to a DNS Root Name Server to determine the Top-Level Domain (TLD) server.
- 4The enterprise DNS resolver queries the designated TLD Name Server to obtain the IP address of the domain's authoritative server.
- 5The enterprise DNS resolver queries the Authoritative Name Server for example.com to retrieve the final A record.
Answer
The correct chronological sequence is: local cache/hosts file check, recursive query to configured enterprise DNS resolver over UDP port 53, iterative query to Root Name Server, iterative query to TLD Name Server, and finally iterative query to Authoritative Name Server for the host IP mapping.
DNS resolution begins locally on the host by evaluating local memory cache and hosts file entries. If unmapped, the host issues a recursive request over UDP port 53 to its configured enterprise DNS resolver. The resolver then carries out iterative queries starting at the Root level, proceeding to the TLD server level, and finally reaching the Authoritative server that returns the definitive resource record mapping.
Step-by-Step Solution
Key Concept
DNS Name Resolution Mechanics and Server Roles