Why Your Website Loads for You but Not for Visitors

You open your site. It loads perfectly. Then a user tells you it's broken — or your monitoring alert fires from a location on the other side of the world. This is one of the most disorienting problems in web operations because the site is clearly working, just not for everyone.

Here's how to systematically diagnose why your site is reachable from some places and not others.

Your Local DNS Cache Has the Old IP

The single most common cause: you recently changed DNS records, your local machine still has the old IP cached, and you're actually connecting to a different server than your visitors are.

# What IP are YOU resolving?
dig yourdomain.com A +short

# What are public resolvers seeing?
dig yourdomain.com @8.8.8.8 A +short
dig yourdomain.com @1.1.1.1 A +short

If these return different IPs, your local cache is stale. Flush it:

# macOS
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

# Windows
ipconfig /flushdns

IP Geoblocking or Firewall Rules

Your server or CDN may be restricting access by geography, IP range, or ISP. This often happens unintentionally — a security rule added to block a spam source that was too broad, or a CDN geo-restriction setting left on from testing.

# Test from the user's region using a VPN or online tool
# Or check directly:
curl -I https://yourdomain.com -H "X-Forwarded-For: IP_FROM_AFFECTED_REGION"

# Check Cloudflare firewall rules if applicable
# Dashboard → Security → Firewall Rules

If users in specific countries or on specific ISPs are affected, geoblocking or a broad IP block rule is likely.

The Server Has Multiple Interfaces and the Wrong One Is Configured

On servers with multiple network interfaces (common with cloud providers), your web server may be listening on a specific IP rather than all interfaces. If your public IP changed — or the server has a different public IP than expected — connections from outside reach a different address than what the web server is bound to.

# What addresses is your web server listening on?
ss -tlnp | grep ':80\|:443'

# Are you listening on all interfaces (0.0.0.0) or a specific IP?
# 0.0.0.0 = all interfaces = accessible from outside
# 192.168.x.x or similar = internal only

CDN Serving Cached Content That Doesn't Match Origin

If you're using a CDN (Cloudflare, CloudFront, Fastly), the CDN may be serving cached responses to most users while you're connecting directly to the origin. If the origin is returning errors but the CDN has a cached success response, you see a working site while users elsewhere get errors — or vice versa.

# Check if Cloudflare is in the path
curl -I https://yourdomain.com | grep -i "cf-ray\|server"

# Check cache status
curl -I https://yourdomain.com | grep -i "cf-cache-status"

If Cloudflare is serving MISS (not cached), users should see the same as you. If HIT, they're getting cached content.

DNS Split Horizon (Corporate Networks)

Some corporate networks and VPNs run internal DNS that overrides public DNS. A developer behind their office network may see the internal/staging version of a site while external users see the public version — or nothing at all if the internal DNS is wrong.

Test from outside your office network (mobile hotspot, home internet) to eliminate this.

Your Browser Is Caching a Success

You visited the site when it was working. Your browser cached the response. The site is now down, but your browser is serving the cached version — so it still looks fine to you.

Test in a private/incognito window with cache disabled:

• Chrome: Incognito + Cmd/Ctrl+Shift+R (hard reload)
• Or use curl to bypass the browser entirely

curl -I --no-cache https://yourdomain.com

How to Check From Multiple Locations

The fastest way to determine the scope of an outage is to check from multiple global locations simultaneously. Tools like dig and curl only tell you what your machine sees.

Domain Monitor checks your site every minute from multiple locations around the world. When your site is accessible from some locations and not others, the monitor shows you which locations are failing — giving you the geographic scope of the problem immediately. Create a free account.

Related Troubleshooting

• DNS_PROBE_FINISHED_BAD_CONFIG Fix
• DNS Propagation Taking Too Long? What to Check First
• Why Your Domain Points to the Wrong Server
• 521 vs 522 vs 524 Cloudflare Errors: What's the Difference?
• Why Website Monitoring Misses Downtime Sometimes