# Learn Website Security and Monitoring

> Sentryx Monitor knowledge pillars for EASM, networking, DNS, TLS, website security, and uptime operations.

Canonical: https://sentryxmonitor.com/learn/
Last updated: 2026-08-08

Security knowledge base

Use these answer-first guides to understand public attack surfaces, network protocols, DNS, TLS, and the monitoring evidence that helps teams act.

- [External Attack Surface Management: A Practical Guide](https://sentryxmonitor.com/learn/external-attack-surface-management/) - Learn what EASM is, how external assets are discovered, how exposure changes, and how continuous monitoring supports an accurate internet-facing inventory.

- [Internet Networking for Security and Monitoring](https://sentryxmonitor.com/learn/networking/) - TCP ports, DNS, TLS, HTTP, and service-failure guides.

- [DNS Security and Monitoring Guide](https://sentryxmonitor.com/learn/dns/) - Learn DNS records, monitoring, DNSSEC, email authentication, TTL behavior, and how DNS changes affect security and availability.

- [TLS and SSL Certificate Security Guide](https://sentryxmonitor.com/learn/tls/) - Learn TLS handshakes, certificate chains, hostname validation, expiration, transparency, wildcard and self-signed certificates, and HTTPS outage prevention.

- [Cybersecurity Glossary](https://sentryxmonitor.com/glossary/) - Detailed protocol, attack-surface, and monitoring definitions.

- [Sentryx Research](https://sentryxmonitor.com/research/) - Methodology and privacy-qualified internet exposure research.

- [External Attack Surface Monitoring](https://sentryxmonitor.com/services/external-attack-surface-monitoring/) - See how Sentryx turns public discovery evidence into an operational monitoring workflow.

- [Website Uptime Monitoring](https://sentryxmonitor.com/services/uptime-monitoring/) - Connect protocol knowledge to continuous endpoint checks and incident evidence.

- [Why Outside-In Monitoring Matters](https://blog.sentryxmonitor.com/why-outside-in-monitoring-matters/) - Learn why public customer experience differs from internal health.

- [How to Monitor SSL Certificate Expiry](https://blog.sentryxmonitor.com/monitor-ssl-certificate-expiry/) - Build an operational certificate-expiry monitoring process.

- [DMARC, SPF, and DKIM Email Trust](https://blog.sentryxmonitor.com/dmarc-spf-dkim-email-trust/) - Understand how public email authentication records work together.

## Related
- [Home](https://sentryxmonitor.com/)