Utilities

Glossary

Learn DNS and networking terms through plain explanations.

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Browse the glossary

Learn DNS and network terms through examples, common issues and related tools.

DNS

The system that translates domain names into IP addresses and other record information.

A

Specifies the IPv4 address of a domain.

AAAA

Specifies the IPv6 address of a domain.

MX

Lists the servers that accept email for a domain. Lower priority values are tried first.

NS

Lists the authoritative DNS servers for a domain.

TXT

Carries text information such as verification data or an email policy.

CNAME

A DNS alias that points a domain name to another domain name.

SOA

Specifies the authority, serial number, and refresh intervals for a DNS zone.

CAA

Restricts the certificate authorities that may issue certificates for this domain.

PTR

The record used for reverse DNS queries from an IP address to a domain name.

TTL

Specifies in seconds how long a DNS record may be cached.

NXDOMAIN

The DNS server reports that the queried domain does not exist. This differs from an empty response for a record type.

NODATA

The domain exists, but no record of the queried type was found.

SERVFAIL

The DNS server could not complete the query. DNSSEC or authoritative server problems may be the cause.

DNSSEC

Uses digital signatures to verify the source of DNS responses and that they have not been altered.

SPF

A TXT policy that specifies which servers may send email on behalf of this domain.

DKIM

Verifies email messages using a cryptographic signature.

DMARC

Specifies the policy for messages impersonating a domain based on SPF and DKIM results.

TLS

Encrypts the connection between a client and server and verifies the server identity through a certificate.

SSL

The older name commonly used for TLS. Modern HTTPS connections use TLS.

HTTPS

HTTP traffic encrypted using TLS.

WHOIS

The traditional protocol for querying domain registration information.

RDAP

A protocol that provides registration information as structured JSON over HTTPS.

PING

Measures network response time using ICMP packets. No response alone does not show that a website is down.

ICMP

A protocol used for network error messages and diagnostics such as ping.

TRACEROUTE

Shows the responding network hops that packets pass through on their way to the target.