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DNS concepts

What is the DNS?

DNS concepts

What is the DNS?

The Domain Name System (DNS) is a critical piece of the Internet. Its primary function is to translate human-readable names into machine-friendly addresses.

What is a DNS stub resolver?

DNS concepts

What is a DNS stub resolver?

A DNS stub resolver is an operating system component that performs DNS name resolution for applications running on a computer or phone.

What is a DNS zone?

DNS concepts

What is a DNS zone?

A DNS zone represents a portion of the DNS namespace owned and managed as a single unit by one organization. The global DNS is composed of many zones.

DNS zone delegation

DNS concepts

DNS zone delegation

Zone delegation is how a parent zone signals to DNS resolvers that authority for a child zone is served by a different set of servers.

What is the DNS root zone?

DNS concepts

What is the DNS root zone?

The DNS is a massive tree of names containing all the names on the Internet. But it has a single starting point: the DNS root zone.

Recursive versus Authoritative DNS

DNS concepts

Recursive vs Authoritative DNS — What's the difference?

There are two types of DNS servers: recursive and authoritative. Authoritative servers host DNS data, while recursive DNS servers perform DNS lookups for users.

An overview of the DNS record types

DNS concepts

All DNS record types

An overview of all the DNS record types. Each DNS record type is briefly explained, and extensive explanations are available in linked articles.

DNS propagation does not exist

DNS

DNS propagation does not exist

A widespread fallacy among IT professionals is that DNS propagates through some network. But DNS propagation does not exist.

DNS record types

A trail of NS records leads to your domain

DNS record types

The NS record

DNS NS records specify the authoritative name server for a domain. Learn how name server record works and how to configure them.

A stack of CNAME records

DNS record types

The CNAME record

DNS CNAME records are used to alias or redirect names in DNS. Learn how canonical names work in DNS, and what their restrictions are.

Delivering the mail

DNS record types

The MX record

The MX or “mail exchange” DNS record type is critical to the delivery of email via SMTP. MX records are used to specify a list of mail servers for a domain.

Mail authentication before TXT records

DNS record types

The TXT record

The TXT or “descriptive text” DNS record type was created to hold human-readable text but now plays a critical role in the prevention of spam on the Internet.

Mapping names into numbers

DNS record types

The A record

The A or “address” DNS record type maps DNS names to IPv4 addresses. Translating names to addresses is one of the most fundamental uses of the DNS.

Mapping names into numbers

DNS record types

The AAAA record

The AAAA DNS record type was created to hold IPv6 addresses. AAAA records, pronounced “quad A records” are similar to A records, but hold a 128-bit IPv6 address instead of a 32-bit IPv4 address.

DNS records replicated across DNS servers

DNS record types

The SOA record

DNS SOA records state that authority for a zone starts at a particular point in the tree of DNS names. Learn how they work and how they impact negative caching.

Service location in the DNS

DNS record types

The SRV record

The SRV or "service locator" DNS record type enables service discovery in the DNS. SRV records allow services to be advertised on specific ports.

Pointer records in the DNS

DNS record types

The PTR record

The PTR or "pointer" DNS record type maps an IP address to a domain name in the DNS. This is called a DNS reverse lookup.

Email and the DNS

SPF in the DNS

Email and the DNS

SPF: A practical guide

Sender Policy Framework (SPF) records in the DNS identify the mail servers allowed to send email for a domain. SPF protects domains from email abuse.

DKIM in the DNS

Email and the DNS

DKIM: A practical guide

DomainKeys Identified Mail (DKIM) adds public key cryptography to email. Email is signed by the sender, and verified by the receiver using the DKIM record.

DMARC for email security

Email and the DNS

DMARC: A practical guide

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is one of the three pillars of modern email security. It protects email senders and recipients from spoofing, spam, and phishing attacks.

MX vs SPF vs DMARC vs DKIM vs BIMI

Email and the DNS

MX vs SPF vs DMARC vs DKIM vs BIMI

Learn about the five DNS records that help control email delivery and spam prevention: MX, SPF, DKIM, DMARC, and BIMI.

How to merge DMARC records

Email and the DNS

How to merge DMARC records

DMARC protect domains from phishing and spam. A domain may have multiple senders for different types of email, but each domain may have only one DMARC record.

Using different DMARC records for subdomains

Email and the DNS

Using different DMARC records for subdomains

DMARC permits only one DMARC record per domain, but subdomains can be used when DMARC policies can't be merged.

Delivering the mail

DNS record types

The MX record

The MX or “mail exchange” DNS record type is critical to the delivery of email via SMTP. MX records are used to specify a list of mail servers for a domain.

Domain names

How does domain name registration work?

Domain names

How does domain name registration work?

Domain registration is the process of making a new DNS zone available on the Internet.

10 tips for picking the perfect domain name

Domain names

10 tips for picking the perfect domain name

Your web address is as important as your brand. We've laid out 10 tips for you to pick the perfect domain name.

Holly SmithPost by Holly Smith

Holly Smith

Finding WHOIS servers using SRV records

Domain names

Finding WHOIS servers using SRV records

Every TLD registry publishes data about registered domain names using WHOIS. 36 registries publish the location of their WHOIS servers using SRV records.

Operations

The life of a DNS query in Kubernetes

Operations

The life of a DNS query in Kubernetes

In Kubernetes, DNS queries follow a specific path to resolve the IP address of a hostname. Here are all the steps and components it goes through.

Steven ReitsmaPost by Steven Reitsma

Steven Reitsma

A pile of clocks representing DNS TTL

DNS

What is a good TTL for DNS?

This article will examine some of the pitfalls that come with low TTLs and will help you select appropriate TTL values.

Command line tools

A specific DNS server in nslookup

Command line tools

How to specify a DNS server in nslookup?

Nslookup uses your system's DNS server by default. You can change by specifying a DNS server in the command itself. Here's how.

Security

Redirecting DNS traffic maliciously

Security

What is the DNS Changer Malware?

The DNS changer malware changed the DNS servers of its victims. It was shut down by the FBI, Estonian police and NASA-OIG in 2011.