DNS
Domain Name System — resolves human-readable names like example.com into IP addresses.
DNS (Domain Name System) is a hierarchical, distributed naming system that translates fully qualified domain names into IP addresses, and the reverse, so devices can locate each other without memorizing numeric addresses. Resolution moves through a recursive resolver, root name servers, TLD servers, and the authoritative name server for the domain. On the Network+ exam, know DNS uses UDP port 53 for standard queries and TCP port 53 for zone transfers or responses exceeding 512 bytes. Don’t confuse a CNAME (alias to another hostname) with an A record (hostname-to-IPv4 mapping); a CNAME cannot coexist with the SOA at a zone apex.
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