Docs › Monitor Types

Monitor Types

is0k supports five check types to cover every layer of your infrastructure.

HTTP / HTTPS All plans

HTTP / HTTPS Monitoring

The most common check type. is0k sends an HTTP request to your URL and validates the response.

What it checks

  • Status code — Configurable (default: 200). Alert if the response code doesn't match.
  • Response time — Measures time to first byte (TTFB). Tracked over time for trend analysis.
  • Keyword match — Optionally check for a string in the response body (e.g., "status":"ok").
  • Custom headers — Send authentication headers or custom request headers.
  • HTTP method — GET (default), POST, PUT, HEAD, OPTIONS.

Configuration example

URL:            https://api.example.com/health
Method:         GET
Expected status: 200
Keyword match:  "status":"healthy"
Timeout:        30s
Retries:        2
Headers:        Authorization: Bearer {${API_KEY}}
Tip: Add a /health endpoint to your API that checks all internal dependencies (database, Redis, etc.) and returns a non-200 status if anything is unhealthy. Then monitor that single endpoint.
TCP Hobby plan+

TCP Port Monitoring

Verifies that a TCP port is open and accepting connections. Useful for databases, mail servers, game servers, and any non-HTTP service.

Common use cases

Service Default Port
PostgreSQL 5432
MySQL 3306
Redis 6379
MongoDB 27017
SMTP 25 / 587
SSH 22

Configuration

Host:  db.example.com
Port:  5432
Timeout: 10s
Ping Hobby plan+

ICMP Ping Monitoring

Sends ICMP echo requests (ping) to verify basic network reachability. Reports round-trip time (RTT) and packet loss.

Useful for: bare-metal servers, IoT devices, VPN endpoints, and network infrastructure where HTTP isn't available.

What it measures

  • Round-trip time (RTT) — How long a packet takes to travel to the host and back
  • Packet loss — Percentage of packets that don't receive a response
DNS Pro plan+

DNS Monitoring

Monitors DNS resolution time and validates that your domain resolves to the expected IP address or value. Catches DNS propagation issues, hijacking, and misconfigured records.

Supported record types

AAAAACNAMEMXTXTNS

Configuration example

Domain:       example.com
Record type:  A
Expected IP:  203.0.113.42   (optional — leave blank to just check resolution speed)
SSL Hobby plan+

SSL Certificate Monitoring

Monitors TLS/SSL certificate expiry and validity. Get warned days or weeks before your certificate expires — never let an expired cert cause an outage.

What it checks

  • Expiry date — Alert 30, 14, and 7 days before expiry
  • Chain validity — Ensure the certificate chain is complete and trusted
  • Hostname match — Verify the cert covers the monitored domain
Warning: An expired SSL certificate causes browsers to show a security error, blocking all users. Always monitor SSL expiry, even for certificates managed by Let's Encrypt (auto-renewal can fail).

Check Intervals

Plan Minimum Interval Max downtime before detection
Starter (Free) 5 minutes Up to ~5 min
Hobby ($7/mo) 3 minutes Up to ~3 min
Pro ($19/mo) 1 minute Up to ~1 min
Business ($49/mo) 30 seconds Up to ~30 sec
Enterprise 10 seconds Up to ~10 sec

Monitoring Regions

Multi-region monitoring checks your service from multiple geographic locations simultaneously. A location-specific outage (e.g., your CDN is down in Europe) shows up as a regional failure while the service appears up from other regions.

US East (N. Virginia)
US West (Oregon)
EU West (Ireland)
EU Central (Frankfurt)
Asia Pacific (Singapore)
Asia Pacific (Tokyo)

Multi-region available on Pro (2 regions), Business (5), and Enterprise (10+) plans.

← Quick Start Alert Channels →