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Difficulty: EasyDNS Lookup and Name Resolution Roles in Enterprise Networks

An enterprise workstation needs to access a web server using its Fully Qualified Domain Name (FQDN). Arrange the steps of the DNS name resolution process in the correct chronological order from first to last.

  1. 1The host checks its local DNS cache and hosts file for an existing name-to-IP mapping.
  2. 2The host sends a recursive DNS query over UDP port 53 to its configured DNS server.
  3. 3The recursive DNS server queries external name servers (Root, TLD, and Authoritative) to resolve the FQDN.
  4. 4The recursive DNS server returns the resolved IP address to the workstation and caches the record.

Answer

The correct sequence of DNS name resolution begins with the client checking its local resolver cache and hosts file, followed by sending a recursive query to the configured DNS server on UDP port 53. The DNS server performs iterative lookups against authoritative root, TLD, and domain servers, and finally returns the resolved IP address back to the requesting workstation.
The name resolution process follows a strict hierarchy. First, local system resources (cache and hosts file) are inspected. If unresolved, the client generates a recursive DNS query to its configured DNS server via UDP port 53. The DNS server resolves the query via external hierarchy (Root, TLD, Authoritative servers) as needed, and lastly sends the reply back to the workstation while saving the mapping in its local cache.

Step-by-Step Solution

1
Check local client sources
Host determines whether the mapping is already known in local memory or local configuration files.
Checking local host cache avoids unnecessary network overhead.
2
Initiate DNS request
Host transmits a UDP packet to port 53 of the primary DNS server.
The client delegates full resolution responsibility to its recursive resolver.
3
Perform recursive server lookup
The internal DNS server communicates with authoritative DNS infrastructure.
The recursive server traverses the DNS hierarchy to find the authoritative answer.
4
Deliver and cache response
The workstation receives the IP address and completes establishing connection to the destination.
Caching speeds up future resolution queries within the TTL period.

Key Concept

DNS Lookup Process and Name Resolution Roles
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Topics

DNS Lookup and Name Resolution Roles in Enterprise Networks

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