Have you ever updated your website's nameservers, only to find that it still doesn't load for half your users? Or worse, have your transactional emails suddenly started landing in the spam folder? The culprit is almost always a misconfigured DNS.
The Domain Name System (DNS) is the phonebook of the internet. If it's broken, your entire digital presence grinds to a halt. In this guide, I’ll show you exactly how to run a comprehensive DNS lookup to diagnose and fix these critical issues.
1. The Essential DNS Records You Need to Check
To understand what's wrong, you first need to know what records dictate your website's behavior:
- A Record: Points your domain to an IPv4 address (your web server).
- AAAA Record: Points to an IPv6 address (increasingly important for modern mobile networks).
- CNAME Record: Creates an alias for another domain name (often used for subdomains like
www). - MX Record: Directs your incoming emails to the correct mail servers.
- TXT Record: Holds text data, most commonly used for SPF (Sender Policy Framework) to prevent email spoofing.
2. Diagnosing Website Loading Issues (A & AAAA Records)
If your site isn't loading after a server migration, you likely have an A record issue. Start by running a Free DNS Lookup. This tool will query the global DNS network and show you exactly what IP your domain is currently pointing to.
Pro Tip: If you recently changed your DNS, remember that propagation takes time due to TTL (Time To Live) caching. It can take anywhere from 5 minutes to 48 hours for global ISPs to see the new IP.
3. Fixing Email Delivery (MX & TXT Records)
If your emails are going to spam, your MX records and SPF TXT records are the first things to investigate.
Run the same DNS Lookup and filter for TXT and MX.
The Most Common SPF Mistake: You can only have ONE SPF record per domain. If you use Google Workspace and Mailchimp, you must combine their SPF includes into a single TXT record. Having multiple SPF records will instantly cause email delivery failures.
4. Checking Domain Registration (Whois)
Sometimes, the issue isn't the DNS at all, but the domain itself. If your domain has expired, all DNS records will stop resolving. Before you spend hours debugging DNS, take 5 seconds to run a Whois Lookup.
This will instantly show you the expiration date, registrar, and status. If it says "Redemption Period," your domain has expired and you need to renew it with your registrar immediately.
The Takeaway
Debugging DNS might seem intimidating, but it always comes down to verifying a few specific records. By keeping a reliable DNS checker in your bookmark bar, you can diagnose outages and email errors in seconds instead of hours.