How long does global DNS propagation take?

Authoritative nameservers update within seconds. Full worldwide propagation depends on the TTL value of your previous records (typically 5 minutes to 24 hours). Lowering your TTL to 300 seconds (5 minutes) 24 hours prior to a DNS migration ensures fast worldwide switchover.

What is a CAA record and why should I configure one?

Certification Authority Authorization (CAA) records specify which Certificate Authorities (such as Let's Encrypt or DigiCert) are allowed to issue SSL certificates for your domain. This prevents rogue or unauthorized SSL certificates from being issued in your domain's name.

Why can't a CNAME coexist with other records at domain apex (@)?

According to RFC 1034, a CNAME record redirects the entire node name to an alias target, meaning no other record types (like MX, NS, or TXT) can exist at the exact same hostname. Since the root apex (@) requires NS and SOA records, a CNAME at the apex is illegal. Modern DNS providers resolve this using ALIAS, ANAME, or CNAME flattening.

What is the difference between A and AAAA records?

An A record maps a hostname to a 32-bit IPv4 address (e.g. 93.184.216.34), while an AAAA record maps a hostname to a 128-bit IPv6 address (e.g. 2606:2800:220:1:248:1893:25c8:1946). Running both on the same hostname creates a dual-stack configuration.

How do MX record priorities work?

MX records include an integer priority number (e.g. 10, 20, 30). Sending mail servers always attempt delivery to the server with the lowest numerical priority first. If the primary mail server is unreachable or offline, the sender falls back to secondary servers with higher numerical priorities.

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DNS Lookup & Record Checker

Query DNS records across all major types (A, AAAA, MX, CNAME, TXT, NS, SOA, CAA, PTR). Inspect reported TTL, mail priorities, SPF strings, and formatted BIND zone files.

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DNS Architecture & Protocol Guide

Understanding DNS Records & Hierarchy

The Domain Name System (DNS) translates human-friendly hostnames (like example.com) into machine-routable IP addresses (like 93.184.216.34). Explore how recursive resolution, authoritative delegation, caching TTLs, and zone records keep the global web connected.

A & AAAA Records: IPv4 vs IPv6

A records map hostnames to 32-bit IPv4 addresses, while AAAA records map hostnames to 128-bit IPv6 addresses. Modern dual-stack websites publish both records simultaneously so IPv6-capable clients automatically prefer faster IPv6 routing routes.

MX Records: Mail Routing & Priority

Mail Exchange (MX) records designate the mail servers authorized to accept inbound email for a domain. Each MX entry has a numerical priority; sending mail transfer agents (MTAs) connect to the lowest priority number first and failover to higher numbers.

TXT Records: SPF, DKIM & DMARC

TXT records hold human and machine-readable strings used for domain ownership verification, Google Search Console validation, and anti-phishing email security standards including SPF authorization strings, DKIM public keys, and DMARC enforcement policies.

CNAME vs ALIAS at Domain Apex

A CNAME creates an alias redirecting one hostname to another. Under RFC 1034, a CNAME cannot coexist with any other record types at the exact same node, which is why bare apex domains (example.com) must use ALIAS, ANAME, or CNAME flattening.

NS & SOA: Authoritative Delegation

NS records specify which authoritative nameservers hold the official DNS zone file for your domain. The SOA (Start of Authority) record contains administrative metadata: the primary master nameserver, administrator email, serial number, and zone refresh timers.

TTL Caching & Propagation Speeds

Time To Live (TTL) sets the validity duration (in seconds) for which recursive resolvers (like Cloudflare 1.1.1.1 or Google 8.8.8.8) cache record responses. When migrating servers, lower your TTL to 300 seconds 24 hours prior to eliminate propagation delays.

DNS Record Types & Protocol Cheat Sheet

Complete technical breakdown of common DNS resource records, their primary functions, and standard recommended TTL parameters.

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Type	Record Purpose	Example Value	Standard TTL	RFC Specification
A	Maps hostname to IPv4 address	93.184.216.34	3600 (1 hour)	RFC 1035
AAAA	Maps hostname to 128-bit IPv6 address	2606:2800:220:1:248:1893:25c8:1946	3600 (1 hour)	RFC 3596
CNAME	Canonical Name alias pointing to another domain	www.example.com -> example.com	3600 (1 hour)	RFC 1034
MX	Mail Exchanger host with priority ordering	10 mail.example.com	3600 (1 hour)	RFC 5321
TXT	Arbitrary text, SPF validation, DKIM public keys	v=spf1 include:_spf.google.com ~all	3600 (1 hour)	RFC 1464 / RFC 7208
NS	Delegates zone to authoritative nameservers	ns1.cloudflare.com	86400 (24 hours)	RFC 1035
SOA	Start of Authority: serial, refresh, retry, expire	hostmaster.example.com 2026090601	86400 (24 hours)	RFC 1035
CAA	Restricts Certificate Authorities permitted to issue SSL	0 issue "letsencrypt.org"	3600 (1 hour)	RFC 8659
PTR	Reverse DNS pointer: IP to verified hostname	4.2.2.1.in-addr.arpa -> resolver.net	86400 (24 hours)	RFC 1035

Dedicated DNS Record Guides & Specifications

Explore comprehensive technical documentation, RFC specifications, BIND syntax, TTL guidelines, and live lookup tools for all 12 DNS record types:

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Frequently Asked Questions

Common questions about DNS resolution, TTL caching, and zone records.

TTL tells recursive resolvers and local caches how many seconds they are permitted to store and serve the record before querying authoritative nameservers again. For example, a TTL of 3600 instructs caches to hold the record for 1 hour before re-checking for updates.