DNS 03
The source provides an overview of several key concepts related to the Domain Name System (**DNS**), starting with an explanation of *delegation**, which is necessary for the decentralized management of domains and involves one entity handing over the responsibility for a subdomain to another. It clarifies that a **zone* represents the part of the domain namespace managed by one or more DNS servers, which makes that server *authoritative* for that specific zone. The text then transitions to discussing **DNS queries**, noting that both clients (resolvers) and servers send queries to resolve domain names, and servers can resolve queries even for zones where they are not authoritative. Finally, the source differentiates between two main types of query modes: **iterative**, where the server only checks local information and does not query other servers, and **recursive**, where the server queries other DNS servers until a final answer is obtained.