DNS and how domain resolution works in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does DNS stand for and what is its main purpose?

DNS stands for Domain Name System. Its main purpose is to translate human-friendly domain names (like example.com) into IP addresses that computers use to identify each other on the network.

intermediate

What is a recursive DNS resolver?

A recursive DNS resolver is a server that receives a DNS query from a client and then takes the responsibility to find the IP address by querying other DNS servers until it gets the answer or an error.

intermediate

Explain the role of root DNS servers in domain resolution.

Root DNS servers are the first step in the DNS lookup process. They don’t know the exact IP but direct the resolver to the appropriate Top-Level Domain (TLD) servers, like those for .com or .org domains.

beginner

What is caching in DNS and why is it important?

Caching in DNS means storing the results of previous DNS queries temporarily. It is important because it speeds up domain resolution and reduces the load on DNS servers by avoiding repeated lookups for the same domain.

intermediate

Describe the difference between authoritative DNS servers and recursive resolvers.

Authoritative DNS servers hold the actual DNS records for domains and provide definitive answers. Recursive resolvers act as intermediaries that query authoritative servers on behalf of clients to find the IP address.

What is the first step a recursive resolver takes when resolving a domain name?

A Query the root DNS servers

B Query the authoritative DNS server

C Return cached IP address

D Send a request to the client

The recursive resolver starts by querying the root DNS servers to find the TLD servers responsible for the domain.

Which DNS server type holds the actual DNS records for a domain?

A Recursive resolver

B Root server

C Authoritative DNS server

D Caching server

Authoritative DNS servers store the real DNS records and provide final answers for domain queries.

Why is DNS caching beneficial?

A It reduces DNS server load and speeds up lookups

B It slows down domain resolution

C It deletes old DNS records

D It increases the number of DNS queries

Caching reduces repeated queries and speeds up the resolution process by storing previous results temporarily.

What does a TLD DNS server do during domain resolution?

A Directs queries to root servers

B Provides IP addresses for all domains

C Caches DNS queries

D Directs queries to authoritative DNS servers for specific domains

TLD servers direct the resolver to the authoritative DNS servers responsible for the specific domain.

Which of the following is NOT part of the DNS resolution process?

A Client sends DNS query

B Client directly queries authoritative DNS servers

C Recursive resolver queries authoritative servers

D Recursive resolver queries root servers

Clients usually query recursive resolvers, not authoritative servers directly.

Explain the step-by-step process of how a domain name is resolved to an IP address using DNS.

Think of it like asking a series of helpers until you find the right address.

Describe the roles of recursive resolvers, root servers, TLD servers, and authoritative servers in DNS.

Imagine a chain of helpers passing your question along until the answer is found.