Network Services

DNS Fundamentals

Learn how DNS resolvers turn user requests into name-server queries, use recursion and referrals, and improve performance with caching.

Intermediate12 min read
Network Services lessonNetworkingPractice

UNTIMED COACHING

Practice before the pressure

Use feedback to correct the model, not merely memorize an option position.

GUIDED PRACTICE

Practice the lesson questions

Answer normal lesson questions without a timer. Every answer includes an explanation, and incorrect answers can be tried again before continuing.

CONCEPT MODELS

See the lesson as a system

Use these visual guides to connect the key ideas before answering the questions.

How DNS Resolution Connects Programs and DataPrograms use resolvers, which combine cached information with name-server responses to obtain requested records.
How DNS Resolution Connects Programs and DataA flow from a user program through a resolver toward cache and name servers, with answers returning to the program.
User programRequests information by domain
ResolverFormulates and coordinates DNS
Local cacheStores prior DNS results
Name serverProvides answers or referrals
DNS Query Controls and OutcomesA query identifies requested records, while recursion settings and response types determine how resolution proceeds.
DNS Query Controls and OutcomesA query enters a name server with domain, type, class, and recursion settings, producing an answer, referral, alias continuation, or error.
DNS queryNames requested record set
Name type classSpecifies requested records
RD and RASeparate request and capability
AnswerSupplies requested information