Website Unavailable or Down? Find the Cause in 5 Minutes

Updated: 2026-10-09

When a site is unavailable, the error message already narrows down where the problem is. Run these four checks from your own machine first:

dig +short example.com                                         # 1. does DNS resolve?
nc -z -w 5 example.com 443 && echo port-open                   # 2. does the server accept connections?
curl -sS -o /dev/null -w '%{http_code}\n' https://example.com/  # 3. what does the web server answer?
echo | openssl s_client -connect example.com:443 -servername example.com 2>/dev/null | openssl x509 -noout -enddate   # 4. is the certificate valid?

What you see	Most likely cause	Look at
"This site can't be reached", `DNS_PROBE_FINISHED_NXDOMAIN`	DNS record missing, domain expired	DNS zone, domain registrar
`ERR_CONNECTION_REFUSED`	Web server not running or firewall	`systemctl status nginx`, firewall rules
`ERR_CONNECTION_TIMED_OUT`	Server down, network or firewall dropping packets	hosting panel, `ping`, provider status page
`502 Bad Gateway`	nginx up, application (PHP-FPM, Node, upstream) down	application service and its logs
`503 Service Unavailable`	Maintenance mode, overloaded or stopped backend	application, load, maintenance flag
`504 Gateway Timeout`	Backend too slow - often the database	slow queries, load
`500 Internal Server Error`	Application error	application error log
`NET::ERR_CERT_DATE_INVALID`	SSL certificate expired	certificate renewal (certbot)
Works for you, not for others	Regional DNS, CDN or routing problem	check from several locations

"SITE_UNAVAILABLE" and "The site is currently unavailable"

These messages are not browser or HTTP errors - they come from the application or platform serving the site:

CMS maintenance or offline mode. Many CMSs show "site is currently unavailable" while in maintenance mode or when they cannot reach their database. In MODX, check the site_unavailable_page and site_status system settings; in WordPress, a leftover .maintenance file in the web root keeps the site in maintenance mode after a failed update.
Database connection failure. Applications often fall back to a generic "unavailable" page when the database login fails or the database server is down. Check the database service and the credentials in the application config.
Hosting account suspended or over its limits. Shared hosting and site builders show their own "site unavailable" page when an account is suspended, unpaid or over its resource limits - the hosting panel will say so.
Upstream or API error codes. Some platforms return SITE_UNAVAILABLE as an error code in API responses when the target site is offline; the fix is on the site being called, not the caller.

Understanding Website Unavailability and Its Impact

Website unavailability occurs when your website becomes inaccessible to users, either completely down or returning errors that prevent normal access. When websites are unavailable, users see errors like "This site can't be reached," "Connection timed out," or HTTP error codes (500, 502, 503, 504), causing immediate business impact, lost revenue, damaged reputation, SEO penalties, and user frustration.

Website downtime can happen for various reasons - server failures, network issues, DNS problems, CDN failures, or regional routing issues. Without proper monitoring from multiple locations, you might not notice availability problems until users report them, which can be too late. Learning how to detect and fix website unavailability quickly is essential for maintaining website uptime and preventing business losses.

How to Detect Website Unavailability Problems

Automatic Detection with Zuzia.app

Zuzia.app automatically monitors website availability from three geographically distributed locations (Poland, New York, Singapore) through its URL monitoring feature. The system:

Checks website availability every few minutes from all three locations
Monitors HTTP response codes and response times
Detects regional availability issues
Stores all availability data historically in the database
Sends alerts when websites become unavailable or return errors
On paid plans, let AI read the task output and alert you only when it spots a problem

You'll receive notifications via email or other configured channels when websites become unavailable or return errors, allowing you to respond quickly before users are significantly impacted.

Manual Detection Methods

You can also check website availability manually using commands that Zuzia.app can execute:

# Check website availability
curl -I https://example.com

# Check HTTP status code
curl -s -o /dev/null -w "%{http_code}" https://example.com

# Check response time
curl -o /dev/null -s -w "Time: %{time_total}s\n" https://example.com

# Check from different locations
curl -I https://example.com --connect-timeout 5

Add these commands as scheduled tasks in Zuzia.app to monitor website availability continuously and receive alerts when issues are detected.

Common Causes of Website Unavailability

1. Server Failures

Server failures can cause complete website unavailability:

Signs:

Website completely inaccessible
No response from server
Connection timeout errors
Server not responding to requests

Detection with Zuzia.app:

Monitor server status and availability
Track server response times
Monitor server resources (CPU, memory, disk)
Set up alerts for server failures

Solutions:

Check server status and logs
Verify server is running
Restart server services if needed
Check server resources (CPU, memory, disk)
Investigate server errors in logs
Consider server redundancy or failover

2. Web Server Service Issues

Web server services (Nginx, Apache, PHP-FPM) can stop or fail:

Signs:

HTTP 502 Bad Gateway errors
HTTP 503 Service Unavailable errors
Web server not responding
Service stopped or crashed

Detection with Zuzia.app:

Monitor HTTP status codes
Track service status
Monitor response times
Set up alerts for HTTP errors

Solutions:

Check web server service status
Restart web server services
Review web server configuration
Check web server logs for errors
Verify service dependencies
Configure automatic service restarts

3. DNS Problems

DNS issues can prevent users from reaching your website:

Signs:

"DNS_PROBE_FINISHED_NXDOMAIN" errors
Website not resolving to correct IP
DNS propagation issues
Incorrect DNS records

Detection with Zuzia.app:

Monitor DNS resolution
Track DNS response times
Verify DNS records
Set up alerts for DNS issues

Solutions:

Verify DNS records are correct
Check DNS propagation
Review DNS configuration
Verify domain configuration
Check DNS provider status
Update DNS records if needed

4. Regional Availability Issues

Websites can be unavailable from specific regions:

Signs:

Website accessible from some locations but not others
Regional routing problems
CDN issues in specific regions
Geographic restrictions

Detection with Zuzia.app:

Compare availability across locations
Monitor regional response times
Track regional availability patterns
Set up alerts for regional issues

Solutions:

Check CDN configuration for affected regions
Verify routing to affected regions
Review geographic restrictions
Check ISP connectivity in affected regions
Optimize CDN for all regions

5. Network Connectivity Issues

Network problems can prevent website access:

Signs:

Connection timeout errors
Network unreachable errors
Slow or intermittent connectivity
Packet loss

Detection with Zuzia.app:

Monitor network connectivity
Track response times
Monitor connection success rates
Set up alerts for connectivity issues

Solutions:

Check network connectivity
Verify firewall rules
Review security group configurations
Check for DDoS attacks
Verify network infrastructure

6. High Server Load

High server load can cause website unavailability:

Signs:

Slow response times
HTTP 503 errors
Server overload
High CPU or memory usage

Detection with Zuzia.app:

Monitor server resources (CPU, memory)
Track response times
Monitor load averages
Set up alerts for high resource usage

Solutions:

Optimize server performance
Scale server resources
Implement load balancing
Optimize application code
Add more server capacity

Step-by-Step Solutions for Website Unavailability

Step 1: Identify the Problem

Use Zuzia.app to identify what's causing website unavailability:

Check Availability Status:
- View Zuzia.app dashboard for current availability status
- Check which locations detect unavailability
- Review HTTP status codes
- Check response times
Review Historical Data:
- Check availability trends over time
- Identify patterns in unavailability
- Compare availability across locations
- Review error patterns
Let AI review the output (paid plans):
- On paid plans, let AI read the task output and alert you only when it spots a problem

Step 2: Check Server Status

Verify server is running and accessible:

Check Server Status:
- Verify server is running
- Check server resources (CPU, memory, disk)
- Review server logs for errors
- Verify server connectivity
Check Web Server Services:
- Verify web server is running (Nginx, Apache)
- Check PHP-FPM or application server status
- Review service logs
- Restart services if needed
Check Server Resources:
- Monitor CPU usage
- Check memory usage
- Verify disk space
- Review system logs

Step 3: Verify DNS Configuration

Check DNS is configured correctly:

Check DNS Records:
- Verify A records point to correct IP
- Check CNAME records if used
- Verify DNS propagation
- Review DNS configuration
Test DNS Resolution:
- Test DNS from different locations
- Verify DNS response times
- Check for DNS errors
- Verify domain configuration
Fix DNS Issues:
- Update DNS records if incorrect
- Wait for DNS propagation
- Verify DNS changes
- Test DNS resolution

Step 4: Check Regional Availability

If website is unavailable from specific regions:

Compare Availability Across Locations:
- Check availability from all monitored locations
- Identify which regions have issues
- Compare response times across regions
Investigate Regional Issues:
- Check CDN configuration for affected regions
- Verify routing to affected regions
- Review geographic restrictions
- Check ISP connectivity
Fix Regional Problems:
- Update CDN configuration
- Fix routing issues
- Remove geographic restrictions if needed
- Optimize CDN for all regions

Step 5: Configure Automatic Actions

Set up automated responses in Zuzia.app:

Service Restart:
- Configure automatic restart when website unavailable
- Automatically restart web server services
- Prevent manual intervention for common issues
Script Execution:
- Execute diagnostic scripts when issues occur
- Run cleanup scripts automatically
- Automate common troubleshooting steps
Team Notifications:
- Alert team members when issues occur
- Escalate critical availability problems
- Document issues automatically

Monitoring Website Availability with Zuzia.app

Automatic Multi-Location Monitoring

Zuzia.app provides comprehensive website availability monitoring:

Multi-location checking: Monitors from Poland, New York, and Singapore
Automatic checking: Availability checked every few minutes
Historical data: All availability data stored for trend analysis
Alerts: Receive notifications when websites become unavailable
HTTP monitoring: Tracks HTTP status codes and response times
Regional detection: Identifies regional availability issues

AI review of task output (paid plans)

On paid plans, AI can read the output of your scheduled tasks and commands, explain it in plain language and alert you only when it spots a problem. Metric alerts work without AI: Zuzia alerts when CPU, RAM or load drifts from the server's normal and forecasts when a disk will fill up.

Custom Availability Monitoring Commands

Add custom commands for detailed availability analysis:

# Check website availability
curl -I https://example.com

# Check HTTP status code
curl -s -o /dev/null -w "%{http_code}" https://example.com

# Check response time
curl -o /dev/null -s -w "Time: %{time_total}s\n" https://example.com

# Check DNS resolution
nslookup example.com

# Check connectivity
ping -c 4 example.com

Schedule these commands in Zuzia.app to monitor availability continuously and receive alerts when issues are detected.

Best Practices for Preventing Website Unavailability

1. Monitor Website Continuously

Don't wait for problems to occur:

Use Zuzia.app for continuous availability monitoring
Monitor from multiple locations
Set up alerts before problems become critical
Review availability trends regularly

2. Monitor All Critical URLs

Monitor important pages, not just homepage:

Homepage and key pages
API endpoints
Admin panels
Checkout and payment pages
Critical subdomains

3. Set Up Redundancy

Implement redundancy to prevent downtime:

Use multiple servers or load balancing
Implement CDN for global availability
Set up database replication
Configure automatic failover

4. Monitor Server Resources

Prevent server overload:

Monitor CPU, memory, and disk usage
Set up alerts for high resource usage
Scale resources before limits are reached
Optimize server performance

5. Regular Maintenance

Perform regular maintenance:

Update server software regularly
Review and optimize configurations
Clean up logs and temporary files
Test backup and recovery procedures

6. Document Procedures

Maintain documentation:

Document troubleshooting procedures
Keep runbooks for common issues
Document escalation procedures
Maintain incident response plans

Troubleshooting Website Unavailability: Complete Workflow

Immediate Response (When Website is Down)

Check Current Status:
- View Zuzia.app dashboard for current availability
- Check which locations detect unavailability
- Review HTTP status codes
- Identify affected regions
Take Immediate Action:
- Restart web server services if safe
- Check server status and resources
- Review recent server logs
- Verify DNS configuration
Monitor Results:
- Check if website becomes available
- Verify all locations can access website
- Ensure no new problems introduced
- Confirm services are running

Long-Term Solutions

Investigate Root Cause:
- Review server logs for errors
- Analyze availability patterns
- Identify recurring issues
- Use AI analysis for insights
Implement Fixes:
- Fix server configuration issues
- Optimize server performance
- Implement redundancy
- Improve monitoring
Prevent Recurrence:
- Set up better monitoring
- Implement automatic failover
- Plan capacity upgrades
- Document solutions

FAQ: Common Questions About Website Unavailability

How do I know if my website is unavailable?

Zuzia.app automatically monitors website availability from three global locations (Poland, New York, Singapore) and sends alerts when your website becomes unavailable or returns errors. You can also check availability manually using commands like curl -I https://example.com or by accessing your website directly. Website unavailability typically shows as connection errors, timeout errors, or HTTP error codes (500, 502, 503, 504).

What should I do immediately when my website is unavailable?

When your website is unavailable, immediately check the Zuzia.app dashboard to see which locations detected the issue, verify if the problem affects all locations or just specific regions, check your server status and logs, restart web server services if safe, verify DNS configuration, and investigate the root cause. If it's a regional issue, check CDN configuration, routing, or geographic restrictions for that specific region.

Can website unavailability cause business losses?

Yes, website unavailability can cause significant business impact including lost revenue from unavailable e-commerce, damaged reputation and user trust, SEO penalties from search engines, lost leads and conversions, and customer frustration. It's essential to monitor website availability continuously and respond quickly to availability issues to minimize business impact.

How can Zuzia.app help prevent website unavailability?

On paid plans, AI can also read task output and alert you only when it spots a problem.

Does AI analysis help with website availability problems?

Can I monitor website availability on multiple URLs simultaneously?

Yes, Zuzia.app allows you to add multiple URLs and all will be monitored simultaneously from all three global agent locations. Each URL has its own alert thresholds, notification settings, and can be configured independently. This makes it easy to monitor your homepage, key pages, API endpoints, subdomains, and other critical URLs from multiple geographic locations.

How often should I check website availability?

Zuzia.app checks website availability automatically every few minutes from each of the three global agent locations. For critical production websites, this frequency is usually sufficient. You can also add custom commands to check availability more frequently if needed. The key is continuous monitoring rather than occasional checks, which Zuzia.app provides automatically.

What's the difference between website unavailability and slow response times?

Website unavailability means your website is completely inaccessible (down), while slow response times mean your website is accessible but takes too long to respond. Both are important - unavailability prevents users from accessing your website, while slow response times create poor user experience. Zuzia.app monitors both availability and response times from all global agent locations.

How can I detect regional availability issues?

Zuzia.app monitors website availability from three global locations (Poland, New York, Singapore), allowing you to compare availability across different regions. If your website is unavailable from one location but accessible from others, it indicates regional issues like CDN problems, routing issues, or geographic restrictions. The dashboard shows availability status from each location, making it easy to identify regional problems.

Can I set up automatic actions when my website becomes unavailable?

Yes, Zuzia.app allows you to configure automatic actions when your website becomes unavailable. You can set up service restarts, script execution, cache clearing, team notifications, and other automated responses. This helps you respond to availability issues automatically without manual intervention, especially useful during off-hours or when immediate response is needed.

How does historical availability data help with capacity planning?

Historical availability data collected by Zuzia.app shows availability trends over time, allowing you to identify patterns in downtime, predict when availability problems might occur, plan infrastructure improvements based on data, verify optimizations are working, and make data-driven decisions about website infrastructure, CDN configuration, and server capacity. On paid plans, AI can also read task output and alert you only when it spots a problem.

Related guides, recipes, and problems

Related guides
- Global website and URL monitoring with multiple agents: guides--website-uptime-monitoring-guide.md, guides--website-url-monitoring-global-agents.md
- Server ping and latency monitoring: guides--server-ping-monitoring-global-agents.md, guides--monitoring-ping.md
Related recipes
- Check website HTTP status and response time from the server: recipes--how-to-check-dns-configuration-linux.md, recipes--monitor-dns-information-linux.md
- Monitor web server error logs (Apache/Nginx): recipes--monitor-apache-error-logs-recent.md, recipes--check-nginx-error-logs-recent.md, recipes--check-nginx-apache-access-logs.md
- Monitor network connectivity, established connections, and errors: recipes--monitor-network-connections-linux.md, recipes--monitor-established-network-connections-count.md, recipes--monitor-network-errors-dropped-packets.md
Related problems
- Network connectivity incidents on Linux servers: problems--network-connectivity-issues-linux.md
- High CPU or memory usage causing overload: problems--high-cpu-usage-server.md, problems--high-memory-usage-server.md
- Expired SSL certificates breaking secure access: problems--expired-ssl-certificate.md