1. Check DNS first
If a site is unreachable for everyone, DNS is the first suspect. Use a DNS lookup tool to confirm the domain still resolves to the expected IP address or hosting provider. A recent DNS change, an expired domain, or a mistaken record edit are the most common causes of a site that was working yesterday and isn't today.
If DNS looks wrong, check who manages the domain's nameservers and DNS records, and confirm no recent change was made without everyone knowing. DNS changes typically need time to propagate, so a very recent change might still be spreading across the internet — but if it's been more than 24-48 hours, something is misconfigured.
2. Confirm the domain hasn't expired
Domain expiration is an embarrassingly common cause of a site going down, especially when renewal is on an old card or an inbox nobody checks. A quick WHOIS lookup shows the expiration date. If a domain has expired, most registrars have a grace period, but the site will not resolve until it's renewed and DNS is confirmed active again.
3. Check the SSL certificate
An expired SSL certificate doesn't always take a site fully offline, but it will show visitors (and some browsers, aggressively) a security warning that functionally kills the site for anyone who sees it. Check the certificate's expiration date directly in the browser or with an SSL checker tool.
4. Check hosting status
If DNS, domain, and SSL are all fine, the next layer is the hosting environment itself. Check for a status page or outage notice from the hosting provider, and confirm the hosting account itself is in good standing (unpaid invoices are a quiet, common cause of suspended hosting). If the account and provider both look fine, the issue may be a server-side resource limit, like storage or database limits being exceeded.
5. Check the application itself
If everything above checks out and the site still won't load correctly, the problem is likely in the application layer: a bad plugin update, a broken deployment, a misconfigured redirect, or a database connection error. This is where error logs, recent changes, and recent updates become the starting point, rather than infrastructure.
What if this becomes a recurring problem, not a one-time fix?
Every item on this checklist is something proactive monitoring can catch before a customer notices: DNS resolution checks, SSL expiry alerts, and uptime checks turn a 2am emergency into a scheduled renewal or a fast, informed fix.