DNS & Infrastructure

DNS (Domain Name System)

Hierarchical naming system that translates domain names into IP addresses.

Nameserver

Server that stores DNS records and responds to DNS queries for a domain zone.

A Record

DNS record mapping a domain name to an IPv4 address.

AAAA Record

DNS record mapping a domain name to an IPv6 address.

CNAME Record

DNS record that creates an alias from one domain name to another canonical name.

MX Record

DNS record specifying the mail server responsible for receiving email for a domain.

TXT Record

DNS record holding arbitrary text data, commonly used for email authentication and domain verification.

NS Record

DNS record that delegates a DNS zone to an authoritative nameserver.

DNS Resolver

Software or service that performs recursive DNS lookups on behalf of clients.

DNS Cache (TTL)

Temporary storage of DNS query results with a Time-To-Live expiration.

Authoritative DNS Server

Server that holds the original DNS records for a zone and provides definitive answers.

DNS Zone File

Text file describing a DNS zone with records for all domains in that zone.

SOA Record

Start of Authority record containing administrative information about a DNS zone.

Subdomain

Domain that is part of a larger domain, created by prepending a label (e.g., blog.example.com).

IP Address

Numerical label (IPv4 or IPv6) assigned to each device connected to a computer network.

Recursive DNS Resolver

Server that performs the full DNS resolution chain on behalf of clients and caches results.

DNS Root Server

Top-level nameservers that direct resolvers to the correct TLD nameservers.

DNS Zone

Administrative partition of the DNS namespace managed by a single authoritative authority.

PTR Record (Reverse DNS)

DNS record that maps an IP address back to a hostname for reverse DNS lookups.

DNS Delegation

Transfer of DNS authority for a child zone to designated nameservers via NS records.

DNS Round Robin

Load-balancing technique using multiple IP addresses on a single hostname to distribute traffic.

DNS Sinkhole

DNS configuration that redirects malicious domains to a controlled IP to block or analyze threats.

EDNS (Extension Mechanisms for DNS)

RFC 6891 extension to the DNS protocol enabling larger messages, DNSSEC, and new option codes.

DNS Amplification Attack

DDoS technique exploiting open DNS resolvers to flood a victim with amplified response traffic.

Negative Caching (NXDOMAIN)

Caching of NXDOMAIN and NODATA DNS responses to prevent repeated queries for non-existent names.