DNS for website owners: what it is, and how it breaks

What DNS actually does

Every website lives on a server with an IP address — a string of numbers like 93.184.216.34. But nobody types IP addresses into a browser. We type domain names: yoursite.com.

DNS — Domain Name System — is the lookup that turns the domain name into the IP address. When someone types yoursite.com in their browser, the browser asks a DNS resolver “what’s the IP address for yoursite.com?” The resolver asks a chain of authoritative servers until it finds an answer, then hands the IP back to the browser, which makes the actual connection.

The whole thing happens in a few hundred milliseconds. You never see it. It just works — until it doesn’t.

The pieces involved

Every domain has four pieces of DNS infrastructure:

1. The registrar — where you bought the domain. GoDaddy, Namecheap, Cloudflare Registrar, Hover, Google Domains (RIP).
2. The nameservers — the servers that hold the authoritative DNS records for your domain. Could be your registrar’s bundled nameservers, or a separate DNS host like Cloudflare, AWS Route 53, or DNSimple.
3. The DNS records — the actual instructions. An A record points your domain to an IP address. A CNAME aliases one domain to another. An MX record routes email. A TXT record holds verification strings.
4. The TTL — Time To Live. How long resolvers should cache a record before asking again. A low TTL (30 seconds) means changes propagate fast but resolvers ask more often. A high TTL (24 hours) means efficient caching but slow propagation.

When any one of these pieces breaks or gets misconfigured, your website appears to disappear — even though the actual server hosting your site is running fine.

How DNS breaks (the common ways)

1. Your domain expired. The most embarrassing failure. If you forget to renew your domain registration, the registrar takes it back, the nameservers stop responding, and your site goes dark globally within hours. The fix is to auto-renew everything, set up multiple notification emails for renewal reminders, and check your registrar dashboard once a quarter.

2. Your nameservers changed (or got changed for you). Sometimes you move DNS hosts — say, from your registrar’s bundled DNS to Cloudflare — and you have to update the nameservers at the registrar. If the new ones aren’t configured yet, or the old ones expire before the new ones answer, you have a window of outage.

3. Someone updated an A record incorrectly. Most common when teams are migrating hosts. The new A record points to the wrong IP, or the old one wasn’t deleted, or a developer fat-fingers 198.51.100.5 as 198.51.100.50. Resolvers cache the bad answer, and your site becomes unreachable until the TTL expires or you fix it.

4. The CDN is misconfigured. Modern sites usually have a CDN (Cloudflare, Fastly, CloudFront) in front of the origin server. The CDN edge IPs change occasionally, and if your DNS hasn’t been updated to match, you end up pointing at IPs that no longer serve your domain.

5. The DNS host went down. Rare but happens — even AWS Route 53 has had multi-hour outages. If your only nameserver host is down, every resolver in the world will fail to find your IP until it comes back. The mitigation is to use multiple DNS hosts in parallel (secondary DNS).

6. DNSSEC misconfiguration. DNSSEC adds cryptographic verification to DNS responses. Done right, it prevents DNS spoofing. Done wrong, it can make your domain resolve nowhere because resolvers can’t validate the signatures. Don’t enable DNSSEC unless you know what you’re doing — or be ready for a 24-hour outage when it breaks.

7. Propagation lag during changes. When you update DNS records, the change has to propagate through caches around the world. With short TTLs this takes minutes. With long TTLs it can take days. During the propagation window, some users hit the old record and some hit the new one — which can look like an outage even though everything is working “somewhere.”

How to spot a DNS problem

DNS outages have a specific signature that distinguishes them from server outages:

• The site “doesn’t exist” rather than failing to load. Browsers show DNS_PROBE_FINISHED_NXDOMAIN or similar.
• Pinging the IP directly works. Pinging the domain fails.
• nslookup yoursite.com (or dig yoursite.com) returns an error or wrong IP.
• Different visitors see different behavior depending on which DNS resolver they use.

You can verify from any computer with dig:

dig yoursite.com

If dig returns no ANSWER SECTION or an obviously wrong IP, that’s your problem. Compare with dig @8.8.8.8 yoursite.com (Google’s public DNS) and dig @1.1.1.1 yoursite.com (Cloudflare’s). If different resolvers return different answers, you’re in a propagation window.

Monitoring DNS

Most uptime monitoring services check the combination of DNS + connection + HTTP response. If any step fails, the check fails. That means you’ll see DNS failures show up as outages even if you don’t have dedicated DNS monitoring.

A few things worth setting up specifically:

• Domain expiration alerts. Most registrars send these but they go to a single email that may not get checked. Set a calendar reminder and multiple email destinations.
• Multi-region uptime checks so you can distinguish DNS propagation issues (some regions work, some don’t) from total outages (all regions fail at once).
• TLS certificate monitoring — separate from DNS but related. An expired domain leads to a broken DNS, which leads to a broken cert.

MyUptimeBot does all of this in one check — every probe exercises DNS resolution, TLS handshake, HTTP response, and SSL expiry. When any layer breaks, you get an alert with details about what failed, not just “site is down.”

What to do when DNS breaks

1. Don’t panic-edit records. A bad DNS edit during an outage usually makes things worse. Confirm the failure first.
2. Check your registrar. Is the domain still registered? Are the nameservers correct?
3. Check your DNS host’s status page. Is Route 53 down? Is Cloudflare having an incident?
4. Use dig to see what resolvers are actually returning. Compare across resolvers.
5. If you made a recent change, the change is the most likely cause. Revert.
6. Wait out the TTL for any fixed record. A 24-hour TTL means up to 24 hours before all resolvers see the corrected record. Reduce your TTL before making changes next time.

Practical hygiene

A few things you can do once, and not think about for years:

• Auto-renew the domain. Make sure the payment card on file works. Add a backup card.
• Set the renewal email to a real inbox that’s checked, not a noreply@ address.
• Use a registrar with a 2-factor login so the domain can’t be stolen via account takeover.
• Use multiple DNS hosts if your site is business-critical. “Secondary DNS” mirroring lets you survive single-provider outages.
• Set short TTLs (60–300 seconds) on records you might change soon. Bump them back up after the change has stabilized.
• Monitor your domain from outside so you find out about DNS failures before customers do.

DNS is invisible when it works. The point of monitoring is to make it visible the moment it breaks — which buys you the hour or two that turns a “we lost half a day of traffic” outage into a “we caught it before anyone noticed” save.