Azure Connection Monitor
What it is
Connection Monitor is an Azure Network Watcher capability that repeatedly tests a defined network path. It can measure connectivity, packet loss, and latency between supported sources and destinations such as VMs, scale sets, URLs, FQDNs, or IP addresses.
Why it exists
A one-time test answers “does it work right now?” Connection Monitor collects evidence over time: when a path became unhealthy, how often it fails, whether latency changed, and which network hop may be contributing.
Key ideas
- Define the intended path. Choose source, destination, test configuration, frequency, thresholds, and the protocol that matches the question: TCP, HTTP, or ICMP. A successful DNS lookup alone does not prove the application port is reachable.
- Source requirements matter. Azure VM and scale-set sources need the Network Watcher extension for end-to-end monitoring. On-premises sources need the documented Azure Arc and monitoring setup. A destination does not need the same source extension.
- Results feed operations. Connection Monitor provides topology/path information and can send metrics to Azure Monitor and logs to Log Analytics, where you can alert on persistent degradation.
- A failed check narrows the investigation; it does not name the cause. Inspect DNS, effective NSG rules, routes, firewall/NVA behavior, destination health, and the application listener.
Northwind example
Northwind monitors the path from its web VM scale set to the private order API with HTTPS checks. An alert fires when the success percentage falls below the selected threshold. Maya sees that the web VMs can resolve the API name but TCP connections fail. She uses the Connection Monitor result as a time-stamped symptom, then checks effective NSG rules, routes, and the API’s listener to find the actual fault.
Exam decision
Use Connection Monitor for ongoing path monitoring and Network Watcher’s point-in-time connection diagnostics when the question is about one specific failure now.
Related
network-watcher · azure-monitor · nsg · route-table