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Review the definitions for terms used across Cloudflare’s DNS documentation.

active zoneA DNS zone that is active on Cloudflare requires changing its nameservers to Cloudflare’s for management.
apex domainApex domain is used to refer to a domain that does not contain a subdomain part, such as (without www.). It is also known as “root domain” or “naked domain”.
DNS filteringDNS filtering uses the Domain Name System to block malicious websites and filter out harmful content, enhancing security and access control.
DNS locationDNS locations are a collection of DNS endpoints which can be mapped to physical entities such as offices, homes, or data centers.
DNS over HTTPSDNS over HTTPS (DoH) is a standard for encrypting DNS traffic via the HTTPS protocol, preventing tracking and spoofing of DNS queries.
DNS over TLSDNS over TLS (DoT) is a standard for encrypting DNS traffic using its own port (853) and TLS encryption.
DNS recordDNS records are instructions that live in authoritative DNS servers and provide information about a domain including what IP address is associated with that domain and how to handle requests for that domain.
DNS serverDNS servers translate human-readable domain names into IP addresses, eliminating the need to remember complex IP addresses.
DNS zoneA portion of the DNS namespace that is managed by a specific organization or administrator.
Domain Name System (DNS)The Domain Name System (DNS) is the phonebook of the Internet. DNS translates domain names to IP addresses.
EDNS Client Subnet (ECS)

ECS is a DNS extension that enables recursive DNS resolvers to include client IP address information in their DNS queries.

Not all resolvers use ECS but, if they do, usually a part of the IP address is omitted. Sending ECS headers is generally intended to reduce latency and speed up content delivery in connection to CDNs and load balancers. The ECS mechanism is specified in RFC 7871.

hostnameThe name given to a server or node on a network, often the public DNS name of a server.
nameserverA nameserver is a dedicated server that translates human readable hostnames into IP addresses. Nameservers like root servers, TLD servers, and authoritative nameservers are fundamental components of the Domain Name System (DNS).