Is It Down Checker Guide

How to Check if a Website is Down

When you can't access a website, the first question is always: "Is it down for everyone, or just me?" This seemingly simple question requires understanding several layers of internet infrastructure including DNS, networking, servers, and CDNs.

Website downtime can be caused by dozens of factors: server crashes, DNS failures, network issues, DDoS attacks, configuration errors, SSL certificate problems, or even ISP-level blocks. Identifying the root cause quickly is essential for resolving the issue.

Quick Check Methods

The fastest way to determine if a site is down for everyone:

1. Use is-it-down.app: Visit is-it-down.app (the dedicated domain for this tool) or httptiger.com/is-it-down.html, enter the URL, and get instant results from multiple global locations
2. Try a different network: Use your phone's cellular data instead of WiFi to rule out local network issues
3. Use a different device: Try accessing from another computer or phone
4. Check social media: Search Twitter for "[sitename] down" to see if others are reporting issues

DNS Issues vs Server Downtime

Understanding the difference between DNS problems and server issues is crucial for troubleshooting.

DNS Issues

DNS (Domain Name System) translates domain names (example.com) into IP addresses (192.0.2.1) that computers can understand. DNS issues mean your browser can't find the server's location.

Symptoms of DNS Problems:

• Error message: "DNS_PROBE_FINISHED_NXDOMAIN" or "Server not found"
• Site doesn't load but accessing by IP address works
• Works on some networks but not others
• Recently changed nameservers or DNS records

How to diagnose DNS issues: For a detailed guide on DNS troubleshooting, see our DNS Checker Guide.

# Check if DNS resolves the domain
nslookup example.com

# Use different DNS servers
nslookup example.com 8.8.8.8  # Google DNS
nslookup example.com 1.1.1.1  # Cloudflare DNS

# Detailed DNS information
dig example.com +trace

Common DNS causes:

• DNS propagation delays (24-48 hours after changes)
• Expired domain registration
• Misconfigured DNS records
• DNS server downtime
• ISP DNS cache issues

Server Downtime

Server downtime means DNS resolves correctly, but the server itself isn't responding or is returning errors.

Symptoms of Server Problems:

• Error message: "Connection refused" or "ERR_CONNECTION_REFUSED"
• HTTP 500, 502, 503, or 504 errors
• Very slow response times followed by timeout
• "This site can't be reached" after DNS resolves

How to diagnose server issues:

# Ping the server
ping example.com

# Check if port 80 (HTTP) is open
telnet example.com 80

# Check if port 443 (HTTPS) is open
telnet example.com 443

# Get detailed connection info
curl -v https://example.com

Common server causes:

• Web server crash (Apache, Nginx, IIS)
• Server overload (too much traffic)
• DDoS attack
• Firewall blocking traffic
• Server maintenance/reboot
• Hosting provider issues

Global vs Local Outages

Determining whether downtime affects everyone or just specific regions/networks is essential for troubleshooting.

Global Outages

The entire site is down for all users worldwide.

Causes:

• Origin server completely offline
• DNS infrastructure failure
• Domain suspended/expired
• SSL certificate expired
• Catastrophic code deployment
• Database server crash

How to identify: Check from multiple locations using is-it-down.app. If all locations report down, it's global.

Regional Outages

Site is down in specific geographic regions but works elsewhere.

Causes:

• CDN (Content Delivery Network) node failure in specific region
• Network routing issues
• Regional ISP problems
• Geo-blocking or firewall rules
• Submarine cable damage affecting specific regions

How to identify: is-it-down.app shows different results from different geographic locations. Some report "up" while others report "down."

Local Outages (Just You)

The site works for everyone except you or your network.

Causes:

• Your ISP having issues
• Local network/router problems
• DNS cache on your device
• Browser cache or cookies
• Firewall or antivirus blocking the site
• VPN or proxy issues

How to identify: is-it-down.app reports site is up, but you can't access it.

How to fix local issues:

1. Clear browser cache and cookies
2. Flush DNS cache:

   # Windows
   ipconfig /flushdns
   
   # macOS
   sudo dscacheutil -flushcache
   
   # Linux
   sudo systemd-resolve --flush-caches

3. Try incognito/private browsing mode
4. Restart your router
5. Change DNS servers: Use Google DNS (8.8.8.8) or Cloudflare (1.1.1.1)
6. Disable VPN/proxy temporarily
7. Disable browser extensions
8. Try a different browser

Common Downtime Scenarios and Solutions

Scenario 1: "502 Bad Gateway"

Meaning: Your web server (Nginx, Apache) received an invalid response from an upstream server (application server, database).

Common causes:

• Application server crashed or restarting
• Database connection timeout
• Proxy misconfiguration
• Firewall blocking internal connections

Solution: Check application server logs, verify database connectivity, restart application services.

Scenario 2: "503 Service Unavailable"

Meaning: Server is temporarily unable to handle requests, usually due to overload or maintenance.

Common causes:

• Planned maintenance
• Traffic surge overwhelming server
• DDoS attack
• Database connection pool exhausted

Solution: Scale up resources, implement rate limiting, enable CDN caching, optimize database queries.

Scenario 3: "Connection Timed Out"

Meaning: Server didn't respond within the timeout period.

Common causes:

• Server completely unresponsive
• Firewall blocking traffic
• Network routing issues
• Server under extreme load

Solution: Verify server is running, check firewall rules, examine network connectivity, review server load.

Scenario 4: Site Loads Without CSS/Images

Meaning: HTML loads but assets (CSS, JavaScript, images) fail to load.

Common causes:

• CDN downtime
• Mixed content warnings (HTTP assets on HTTPS page) - check your SSL certificate configuration
• Broken file paths
• Asset server issues

Solution: Check CDN status, fix mixed content issues, verify asset URLs, and check asset server connectivity. Use our broken link checker to identify missing resources.

Monitoring and Prevention

Implement Uptime Monitoring

Don't wait for users to report downtime. Use monitoring tools:

• Status Tiger: statustiger.com - Professional uptime monitoring with 5-minute checks
• Pingdom: Paid service with detailed performance monitoring
• UptimeRobot: Free monitoring for up to 50 monitors

Set Up Alerts

Configure notifications via:

• Email alerts
• SMS/text messages
• Slack/Discord webhooks
• PagerDuty for on-call rotations

Create a Status Page

Communicate with users during outages using a status page hosted separately from your main site. Status Tiger provides easy status page creation.

Build Redundancy

• Use a CDN: Cloudflare, Fastly, or CloudFront distribute content globally
• Implement load balancing: Distribute traffic across multiple servers
• Database replication: Maintain standby database servers
• Multi-region hosting: Host in multiple geographic locations
• Failover DNS: Automatically route to backup servers if primary fails

When to Call for Help

Some downtime scenarios require immediate expert assistance:

• DDoS attack: Contact hosting provider and consider DDoS mitigation services
• Data breach/hack: Isolate affected systems, contact security professionals
• DNS hijacking: Contact domain registrar immediately
• Prolonged unexplained downtime: Escalate to hosting provider's emergency support

Conclusion

Website downtime is inevitable, but understanding how to quickly diagnose the cause dramatically reduces recovery time. The difference between DNS issues, server problems, and local connectivity issues determines your troubleshooting path.

Tools like is-it-down.app help you immediately determine if downtime is global, regional, or local. Combined with proper monitoring and redundancy, you can minimize the impact of outages on your users and business.