Critical Components of Website Monitoring, A System Administrator's Handbook

This comprehensive guide outlines the essential components that system administrators must monitor to maintain optimal website performance and reliability. Each section details specific metrics, their significance, and what constitutes healthy values.

1. Server-Level Monitoring

CPU Usage

What to Monitor:
Overall CPU utilization percentage
Load averages (1, 5, and 15-minute intervals)
Per-process CPU consumption
CPU throttling instances
Healthy Ranges:
Average CPU usage should stay below 70%
Load averages should not exceed number of CPU cores
No sustained periods of 100% utilization
Monitor for unusual spikes during normal operations

Memory Usage

What to Monitor:
Available physical memory
Swap space usage
Memory usage per process
Page faults and swap rates
Healthy Ranges:
Available memory should not drop below 20%
Swap usage should be minimal
No continuous swap in/out operations
Monitor for memory leaks in long-running processes

Disk Performance

What to Monitor:
Disk space usage and trending
I/O operations per second (IOPS)
Read/write latency
Inode usage
Healthy Ranges:
Maintain at least 20% free disk space
Average I/O latency under 10ms
Inode usage below 80%
Monitor for unexpected growth patterns

2. Network Monitoring

Connectivity

What to Monitor:
Network interface status
Packet loss rates
Network latency
Bandwidth utilization
Healthy Ranges:
Packet loss should be near 0%
Latency should be consistent with baseline
Bandwidth usage under 80% of capacity
No interface errors or collisions

DNS Health

What to Monitor:
DNS resolution time
DNS record accuracy
TTL compliance
DNS propagation
Healthy Ranges:
DNS resolution under 100ms
All records matching expected values
No failed DNS queries
Consistent resolution across global locations

SSL/TLS Certificates

What to Monitor:
Certificate expiration dates
SSL/TLS protocol versions
Cipher suites
Certificate chain validity
Critical Checks:
Minimum 30-day warning before expiration
No weak cipher suites enabled
Complete and valid certificate chain
Regular security assessment of SSL configuration

3. Application-Level Monitoring

Web Server Performance

What to Monitor:
Request processing time
Active connections
Error rates
Worker/thread status
Healthy Ranges:
Request processing under 200ms
Error rates below 1%
Connection queue length within normal limits
Worker pool utilization under 80%

Database Performance

What to Monitor:
Query response times
Connection pool status
Lock contentions
Index usage
Query cache hit rates
Healthy Ranges:
Query execution time within defined SLAs
Connection pool utilization under 80%
Minimal lock wait times
Cache hit rates above 80%

Application Response Times

What to Monitor:
Time to First Byte (TTFB)
Page load times
API response times
Resource loading times
Healthy Ranges:
TTFB under 200ms
Page load under 3 seconds
API responses under 500ms
Static resource loading under 100ms

4. Security Monitoring

Access Patterns

What to Monitor:
Login attempts
Failed authentications
Traffic patterns
Administrative actions
Red Flags:
Unusual login patterns
Brute force attempts
Unexpected traffic spikes
Unauthorized access attempts

Security Headers

What to Monitor:
HTTP security headers
Content Security Policy (CSP)
CORS configuration
XSS protection headers
Best Practices:
All security headers properly configured
CSP without unsafe-inline/unsafe-eval
Strict CORS policies
Regular security header audits

5. Content Monitoring

Static Content

What to Monitor:
Resource availability
Cache status
Content integrity
CDN performance
Healthy Indicators:
All resources accessible
Proper cache headers
Content matching checksums
CDN serving expected content

Dynamic Content

What to Monitor:
API endpoints
Form submissions
Search functionality
User authentication flows
Critical Checks:
All endpoints responsive
Forms processing correctly
Search results relevant
Authentication working as expected

6. Business Transaction Monitoring

User Flows

What to Monitor:
Registration process
Login sequence
Checkout process
Critical user journeys
Success Metrics:
Complete flow completion
Expected response times
Error-free transactions
Proper state management

Error Tracking

What to Monitor:
JavaScript errors
Server-side errors
404 errors
API errors
Healthy Ranges:
Minimal JavaScript errors
Server errors below 0.1%
404s limited to expected cases
API errors properly handled

7. Performance Optimization

Resource Optimization

What to Monitor:
Image optimization
Script loading
CSS delivery
Font loading
Best Practices:
Images properly sized and compressed
Scripts loaded efficiently
CSS optimized and minified
Font display optimization

Caching Effectiveness

What to Monitor:
Browser cache usage
Server-side cache hit rates
CDN cache performance
Application cache status
Optimal Ranges:
High browser cache hit rates
Server cache utilization above 80%
CDN offloading majority of traffic
Appropriate cache TTLs

Implementation Recommendations

Establish Baselines
Document normal performance patterns
Set appropriate thresholds
Create baseline metrics for all components
Regular baseline reviews and updates
Alert Configuration
Define clear alerting thresholds
Implement alert severity levels
Configure appropriate notification channels
Avoid alert fatigue through proper tuning
Documentation
Maintain updated monitoring documentation
Document all custom monitoring solutions
Keep runbooks current
Regular review and updates of procedures
Regular Reviews
Monthly performance reviews
Quarterly capacity planning
Annual monitoring strategy assessment
Regular tool and process evaluation

Effective website monitoring requires attention to multiple layers of the technology stack. By monitoring these critical components, system administrators can ensure optimal website performance, reliability, and security. Regular review and adjustment of monitoring strategies ensure continued effectiveness as technology and requirements evolve.