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Difficulty: MediumDNS Lookup and Name Resolution Roles in Enterprise Networks

An enterprise host needs to resolve the IP address of an internal web application server (app.corp.local) after the local cache has expired. Place the steps of the name resolution process in the correct chronological order from first to last.

  1. 1The host checks its local OS DNS client resolver cache and local hosts file for a matching entry.
  2. 2The host encapsulates a recursive DNS query in a UDP datagram with destination port 53 and sends it to its primary configured DNS server.
  3. 3The enterprise DNS server receives the query and checks its authoritative DNS zones for the corp.local domain.
  4. 4The DNS server formulates an authoritative response packet containing the requested IPv4 Address (A) record.
  5. 5The host receives the DNS response packet and stores the IP address mapping in its local DNS resolver cache.

Answer

The correct sequence of DNS name resolution steps is: 1) The host checks its local OS DNS client resolver cache and local hosts file. 2) The host encapsulates a recursive DNS query in a UDP datagram with destination port 53 and sends it to its primary configured DNS server. 3) The enterprise DNS server receives the query and checks its authoritative DNS zones. 4) The DNS server formulates an authoritative response packet containing the requested A record. 5) The host receives the DNS response packet and stores the IP address mapping in its local DNS resolver cache.
The correct order follows the standard host-to-server DNS name resolution flow: first, local host resources (cache and hosts file) are inspected. If unresolved, the client sends a recursive UDP query (destination port 53) to its configured local DNS server. The DNS server processes the query against its zone database, generates an authoritative response containing the A record, and returns it to the host. Finally, the host receives the response and caches the IP address locally.

Step-by-Step Solution

1
Evaluate local host resolution mechanisms.
Local resolver cache and hosts file are queried first prior to generating outbound network requests.
Checking local host memory avoids unnecessary network traffic and reduces latency.
2
Transmit DNS request over the local network connection.
A UDP datagram targeted to destination port 53 is forwarded to the designated local DNS server.
Standard DNS queries use UDP port 53 for low-overhead client-to-server communications.
3
Process query at the targeted enterprise DNS server.
The server checks its local authoritative zone files for matching domain records.
Because the domain is internal (corp.local), the internal DNS server acts as the authoritative source.
4
Build DNS server response payload.
An authoritative DNS answer payload containing the IPv4 (A) record is created.
The server must supply the mapped IP address back to the requesting client.
5
Process response on the requesting client host.
The client receives the response and caches the entry according to the record's Time-to-Live (TTL).
Caching allows subsequent applications on the host to reuse the resolved IP address without repeating the DNS lookup.

Key Concept

Client DNS resolution sequence and DNS server roles
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Topics

DNS Lookup and Name Resolution Roles in Enterprise Networks

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