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Certificate Monitoring Best Practices

The practices below cover common use cases, organizational strategies, and managing certificate monitoring at scale.

Organizing Monitors with Tags​

Tags help you filter, search, and manage monitors efficiently. Develop a consistent tagging strategy across your organization:

Environment Tags: Use production, staging, development, and qa to distinguish between service tiers. This allows you to quickly filter critical production services or apply different alert thresholds.

Service Type Tags: Apply tags like webserver, mailserver, database, ldap, api, cdn, and loadbalancer to group similar services. This helps when troubleshooting service-specific certificate issues.

Team or Ownership Tags: Use devops, platform, security, engineering, or specific team names to identify who manages each service. Route alerts to the appropriate teams through dedicated contact groups.

Geographic or Location Tags: Apply tags like us-east, eu-west, datacenter-1, aws, azure, on-prem to track where services are deployed. This is especially useful for distributed infrastructure.

Criticality Tags: Mark services with critical, high-priority, or customer-facing to identify which certificate expirations would cause the most significant impact.

Combine multiple tags for powerful filtering. For example, tag a monitor with production, webserver, aws, us-east, and critical to fully describe its context.

Profile Strategies for Different Environments​

Create separate monitoring profiles for different use cases rather than using a single profile for everything:

Production Profile:

  • Aggressive thresholds: 90, 60, 45, 30, 15, 7, 3, 1, 0 days
  • Enable all alert types (expiration, name verification, CA verification, integrity, connection, CAA records)
  • Multiple contact groups for redundancy
  • Use case: Customer-facing services where downtime is unacceptable

Staging Profile:

  • Standard thresholds: 30, 15, 7, 0 days
  • Disable name verification if using non-production hostnames
  • Disable CAA record alerts for internal services
  • Single contact group for the engineering team
  • Use case: Pre-production testing environments

Development Profile:

  • Minimal thresholds: 30, 7, 0 days
  • Disable CA verification for self-signed certificates
  • Disable name verification and CAA alerts
  • Configure private CAs for internal PKI
  • Use case: Developer workstations and test environments

Internal Services Profile:

  • Standard thresholds: 60, 30, 15, 7, 0 days
  • Configure private CAs for internal certificate authorities
  • Assign monitoring agents for private network access
  • Disable CAA alerts for services not on public DNS
  • Use case: Internal LDAP, databases, and private APIs

Long-Lived Certificate Profile:

  • Extended thresholds: 90, 60, 45, 30, 15, 7, 0 days
  • All alerts enabled
  • Use case: Certificates with 1-2 year validity that require lengthy procurement processes

When to Use Monitoring Agents vs Public Monitoring​

Use Public Monitoring (Default) When:

  • Services are accessible from the public internet
  • You want to verify certificates from an external perspective (how customers see them)
  • Services are behind load balancers with public IP addresses
  • Simplicity is preferred - no additional infrastructure to deploy

Use Monitoring Agents When:

  • Services are on private networks (RFC 1918 addresses: 10.x.x.x, 172.16-31.x.x, 192.168.x.x)
  • Services are behind firewalls or VPNs without public access
  • You need to monitor from specific geographic locations for compliance
  • You want to control the source IP addresses for security or allowlisting
  • You need redundancy across multiple network paths

Hybrid Approach: Monitor the same service from both public infrastructure and internal agents to verify both external and internal perspectives. This catches issues like split-horizon DNS, firewall misconfigurations, or certificate mismatches between internal and external endpoints.

Balancing Alert Thresholds​

Choose alert thresholds based on your certificate renewal process:

Automated Renewal (Let's Encrypt, ACME):

  • Use shorter thresholds: 30, 15, 7, 0 days
  • Certificates renew automatically every 60-90 days
  • Focus on detecting renewal failures rather than advance warnings

Manual Renewal with Quick Turnaround:

  • Use standard thresholds: 60, 30, 15, 7, 0 days
  • Provides advance warning while avoiding alert fatigue
  • Suitable for most commercial certificate providers

Manual Renewal with Approval Process:

  • Use aggressive thresholds: 90, 60, 45, 30, 15, 7, 3, 1, 0 days
  • Long procurement cycles require maximum advance notice
  • Common in enterprises with security review boards or budget approval requirements

Testing or Short-Lived Environments:

  • Use minimal thresholds: 7, 0 days or even just 0 days
  • Reduces noise for environments that may be torn down before certificates expire

Managing Internal vs External Services​

External/Public Services:

  • Validate against public CAs only
  • Enable all alert types including CAA record validation
  • Monitor from public infrastructure to match customer experience
  • Use production-level alert thresholds
  • Examples: Public websites, customer APIs, email servers accepting external mail

Internal Services:

  • Configure private CAs for internal PKI validation
  • Disable CAA alerts if not using public DNS
  • Deploy monitoring agents on internal networks
  • May disable name verification if using IP addresses
  • Examples: Internal LDAP, databases, private APIs, development services

DMZ or Hybrid Services:

  • Monitor from both public and internal perspectives
  • Validate against both public and private CAs if using mixed infrastructure
  • Carefully configure hostname validation for split-horizon DNS
  • Examples: Web applications with public frontend and private backend, mail servers with both internal and external interfaces

Consolidating Monitoring​

When to Monitor Individual Instances:

  • Each instance has a unique certificate
  • Different teams manage different instances
  • Geographic distribution requires separate certificates
  • Compliance requires monitoring each endpoint

When to Monitor Load Balancers Instead:

  • All backend servers use the same certificate
  • Load balancer terminates TLS (backend is HTTP)
  • Reduces monitor count and simplifies management
  • Billing optimization: one monitor instead of many

When to Monitor Both:

  • Load balancer and backend servers have different certificates
  • End-to-end TLS encryption (load balancer re-encrypts to backends)
  • Verify both external customer experience and internal backend health

Cost Management​

At $0.01 per monitor per day, with one HTTPS monitor free on every account, costs scale with the number of active monitors. See billing details for more information.

Strategies to manage costs:

  • Audit monitors regularly and archive obsolete or decommissioned services (archived monitors aren't billed, and keep their history)
  • Use tags to identify and clean up old development or test monitors
  • Monitor load balancers instead of individual backend servers where appropriate
  • Consolidate similar services under a single monitor when they share certificates
  • Focus monitoring on customer-facing and critical services rather than every possible endpoint

Do Not Compromise on:

  • Production certificate monitoring - expired certificates cause outages
  • Services with manual renewal processes - automation prevents costly mistakes
  • Customer-facing services - reputation and trust are more valuable than monitoring costs

Review and Maintenance​

Weekly: Check the Findings page for monitors with issues. Address connection failures, validation errors, and certificates approaching expiration; fixing one finding often clears it on several monitors at once.

Monthly: Review your monitors list for obsolete services. Audit tag usage for consistency, verify contact groups have current team members, and check that monitoring agents are running current versions.

Quarterly: Evaluate profile configurations and alert thresholds. Review private CA expiration dates and plan renewals. Assess monitoring costs and verify all critical services have monitoring configured.

After Infrastructure Changes: Add monitors for newly deployed services and archive monitors for decommissioned ones. Adjust monitoring agents if network topology changes and update contact groups when team membership changes.

Multi-Team Organizations​

Centralized Management:

  • Security or platform team manages all monitors and profiles
  • Standardized tagging and naming conventions
  • Consistent alert thresholds across the organization
  • Pros: Consistency, oversight, cost control
  • Cons: Bottleneck for changes, may not fit all team needs

Distributed Management:

  • Individual teams manage their own monitors
  • Shared profiles and contact group conventions
  • Tag-based filtering for each team's services
  • Pros: Team autonomy, faster changes, team-specific configuration
  • Cons: Potential inconsistency, requires coordination

Hybrid Approach:

  • Platform team provides standard profiles and guidelines
  • Individual teams create and manage their own monitors
  • Shared tagging taxonomy for cross-team visibility
  • Platform team monitors critical shared infrastructure
  • Best of both approaches for most organizations