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Difficulty: MediumDNS Infrastructure and Record Types

A workstation on an enterprise network needs to resolve the fully qualified domain name `app.partner-net.com` for the first time, starting with an empty local DNS cache. Place the steps of the standard DNS resolution process in the correct chronological order, from the initial client request to the final IP address response.

  1. 1The client stub resolver sends a recursive DNS query for `app.partner-net.com` to its configured local recursive DNS server.
  2. 2The local recursive resolver sends an iterative query for `app.partner-net.com` to a Root DNS Name Server (`.`).
  3. 3The Root DNS Name Server responds to the local recursive resolver with a referral to the `.com` Top-Level Domain (TLD) Name Servers.
  4. 4The local recursive resolver queries the `.com` TLD Name Server and receives a referral to the authoritative Name Server for `partner-net.com`.
  5. 5The local recursive resolver queries the authoritative Name Server for `partner-net.com` and receives the requested A record IP address, returning it to the client.

Answer

The correct chronological sequence for resolving an uncached domain name is: 1) Client stub resolver sends a recursive query to the local DNS server, 2) Local resolver sends an iterative query to a Root Name Server, 3) Root Name Server responds with a referral to the TLD Name Server, 4) Local resolver queries the TLD Name Server and receives a referral to the Authoritative Name Server, and 5) Local resolver queries the Authoritative Name Server to receive the final host A record mapping and sends it back to the client.
DNS resolution follows a top-down hierarchical tree structure when no cached records exist. The client sends a recursive query to its configured local recursive resolver. The local resolver then performs iterative queries by first asking a Root Name Server (`.`), receiving a referral to the `.com` TLD server, asking the TLD server, receiving a referral to the domain's authoritative server, and finally querying the authoritative server to obtain the final Host (A) record mapping.

Step-by-Step Solution

1
Client initiates request
Recursive query sent to local recursive resolver
The client application (e.g., web browser) invokes the stub resolver to resolve `app.partner-net.com`.
2
Local resolver queries Root hierarchy
Iterative query sent to Root server (`.`)
The local recursive server assumes responsibility for resolving the query step-by-step starting at the DNS root.
3
Root server refers to TLD
Referral to `.com` TLD name servers received
Root servers hold delegations for top-level domains and direct the query to the `.com` infrastructure.
4
Resolver queries TLD server
Referral to authoritative server for `partner-net.com` received
TLD servers maintain records for domain registrations within their top-level domain and delegate responsibility to the domain's specified name servers.
5
Resolver queries Authoritative server
Final A record received and delivered to client
The authoritative server contains the master zone record (A record) for `app.partner-net.com`, providing the definitive IP address mapping.

Key Concept

Recursive vs. Iterative DNS Resolution Hierarchy Flow
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Topics

DNS Infrastructure and Record Types

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