DNS records are the underlying configuration that makes domains work. They tell the internet where your website lives (A records), where to send your email (MX records), and how to verify your ownership of various services (TXT records). Understanding how to read and check these records is essential for web professionals, developers, and anyone managing multiple domains.
This guide covers every major DNS record type, how to check them, and how to troubleshoot common DNS problems.
Check Domain Availability Before DNS Setup
Before configuring DNS, confirm your domains are properly registered. Bulk Domain Checker verifies availability for hundreds of domains at once.
Add to Chrome — FreeDNS Record Types Reference
| Record Type | Purpose | Example |
|---|---|---|
| A | Maps domain to IPv4 address | yourdomain.com → 93.184.216.34 |
| AAAA | Maps domain to IPv6 address | yourdomain.com → 2606:2800:220:1:: |
| CNAME | Alias pointing to another domain | www → yourdomain.com |
| MX | Mail server routing | Priority 10 → mail.yourdomain.com |
| TXT | Verification text, SPF, DKIM | v=spf1 include:_spf.google.com ~all |
| NS | Nameservers for the domain | ns1.namecheap.com |
| SOA | Start of authority (admin info) | Serial number, refresh interval |
| SRV | Service location records | Used for VoIP, Microsoft 365 |
| PTR | Reverse DNS (IP to domain) | 34.216.184.93 → yourdomain.com |
| CAA | Certificate authority authorization | Restricts which CAs can issue SSL |
Tools for Checking DNS Records
MXToolbox (Browser Tool)
MXToolbox (mxtoolbox.com) is the most popular browser-based DNS diagnostic tool. It provides lookup tools for every record type plus advanced diagnostics for email delivery (SPF, DKIM, DMARC), blacklist checks, and SMTP server testing.
How to use:
- Go to mxtoolbox.com
- Type your domain in the search box
- Select the record type from the dropdown (MX Lookup, A Lookup, etc.)
- Click the lookup button
Google Public DNS Lookup
Google provides a simple DNS lookup at dns.google/query. It's less feature-rich than MXToolbox but is useful as a second check against Google's own resolver, which is what most users hit when browsing.
DNSChecker.org (Propagation Checker)
After making DNS changes, DNSChecker.org shows whether the update has propagated globally. It queries nameservers in dozens of countries and shows which have the new record and which still show the old one. Invaluable after migrations.
Command Line DNS Lookup (Windows)
Command Line DNS Lookup (Linux/macOS)
Understanding Key DNS Records
A Records — Website Routing
The A record is the most fundamental DNS record — it maps your domain name to an IP address. When someone types your domain into a browser, DNS resolves the A record to find the server's IP address.
You can have multiple A records for the same domain to route traffic to multiple servers for load balancing, or for different subdomains pointing to different servers.
MX Records — Email Routing
MX records control where email sent to your domain gets delivered. Multiple MX records with different priority values create redundancy — if the primary mail server is unavailable, email routes to the backup.
Priority values are relative: lower number = higher priority. Email tries to deliver to priority 10 before priority 20.
TXT Records — Verification and Policy
TXT records serve multiple purposes:
- SPF (Sender Policy Framework): Specifies which mail servers are authorized to send email from your domain
- DKIM (DomainKeys Identified Mail): Public key for email signature verification
- DMARC: Policy for handling SPF/DKIM failures
- Domain verification: Google Search Console, Facebook, and other services use TXT records to verify domain ownership
CNAME Records — Aliases
CNAME records create aliases that point to another domain name. The www subdomain is commonly set as a CNAME pointing to the root domain or to a CDN edge hostname.
DNS Propagation and TTL
When you make a DNS change, it doesn't instantly update worldwide. Nameservers cache DNS records for the duration of the TTL (Time to Live) value. After TTL expires, nameservers fetch fresh records from your authoritative nameserver.
Standard TTL values:
| TTL Value | Duration | Use Case |
|---|---|---|
| 300 | 5 minutes | Before planned DNS changes |
| 3600 | 1 hour | Standard for most records |
| 14400 | 4 hours | Common for A records |
| 86400 | 24 hours | Stable, rarely-changing records |
Common DNS Problems and Solutions
| Problem | Likely Cause | Solution |
|---|---|---|
| Website not loading | Missing or wrong A record | Check A record points to correct server IP |
| Email not delivering | Missing or wrong MX record | Verify MX records match your email provider's settings |
| SSL certificate error | Domain doesn't resolve to expected IP | Ensure A record is stable before issuing SSL |
| Changes not updating | DNS propagation still in progress | Wait for TTL to expire; use DNSChecker to monitor |
| Email marked as spam | Missing SPF/DKIM/DMARC records | Add proper TXT records for email authentication |
Start With Domain Availability
Before configuring DNS, make sure your domain portfolio is complete. Check availability for all your domains at once with Bulk Domain Checker.
Install FreeFrequently Asked Questions
How do I check DNS records for a domain?
Use MXToolbox.com (browser-based, no install needed), Google's DNS lookup at dns.google, or command line tools: "nslookup domain.com" on Windows, or "dig domain.com ANY" on Linux/macOS. These show A records, MX records, CNAME, TXT, NS records, and more.
What are the different types of DNS records?
Key types include: A (IPv4 address), AAAA (IPv6 address), CNAME (alias to another domain), MX (email server routing), TXT (verification and email policy), NS (nameservers), SOA (Start of Authority), SRV (service location), PTR (reverse DNS), and CAA (certificate authority authorization).
How long does DNS propagation take?
DNS changes typically propagate worldwide within 24–48 hours, though many changes take effect within 1–4 hours. The TTL (Time to Live) value on your DNS records determines how long nameservers cache old records. Lower your TTL to 300 seconds before planned migrations to speed up propagation.
Why would DNS records fail to resolve?
DNS resolution failures can occur due to: incorrect or missing records, propagation delays after recent changes, expired domain registration, nameserver misconfiguration, DNSSEC validation failures, or local DNS cache issues. Use DNSChecker.org to see if records are propagated globally and check if your local DNS cache needs flushing.
What does an MX record do?
An MX (Mail Exchange) record directs email sent to your domain to the correct mail server. Multiple MX records with different priority values provide redundancy — if the primary server is unavailable, email routes to backups. Incorrect or missing MX records cause complete email delivery failure.
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