Don't Panic — Microsoft Azure Networking

Microsoft Azure Networking gets a workload's traffic to the right place, by the right path, with the right permission. That sounds like one job until a connection fails and six components politely insist that the problem belongs to somebody else.

The useful map is a chain: a name becomes an address, a route chooses a path, a security control permits traffic, and a frontend delivers it to a service. Azure Virtual Network is the private regional network where that chain starts. Its subnets are not merely drawers full of IP addresses. They are where address planning meets route tables and network security groups, which is a surprisingly consequential way for a drawer to behave.

The first surprise is that these layers do not substitute for one another. A route can send traffic toward an address without granting access. A network security group can allow a port without creating a route. A DNS response can be perfectly valid while pointing to the public address when the intended destination is a private endpoint. A connection that looks allergic to networking can therefore be accurately following the wrong instruction.

Azure Private Link gives a supported service a private endpoint, which is a private IP address in a consumer subnet. That gives the path a private destination. It does not persuade every client to resolve the service name to that destination. Private DNS zones, virtual-network links, and forwarding must agree with the topology. The endpoint is not broken if the name points elsewhere; it is merely being misunderstood with great confidence.

Peering connects VNets but does not create transit through a hub. VPN Gateway and ExpressRoute choose different hybrid transports, but neither rescues overlapping address ranges or an untested failover. Load Balancer, Application Gateway, Front Door, and Traffic Manager distribute traffic at different scopes and layers. A health probe decides whether a backend gets new traffic; it cannot repair the backend's appetite for failure.

When the path breaks, start with the source, destination, protocol, and port. Resolve the name from the source context. Check the returned address, effective routes in both directions, network security groups, and any firewall or frontend. Network Watcher supplies focused evidence such as next hop, IP flow verification, connection troubleshooting, and continuous monitoring. Each answer is narrow on purpose.

Read the Intro for the complete connection model and service choices. Use Slides when the relationships need a compact visual map, Cheatsheet when a comparison or diagnostic sequence is needed, and Field Notes when shared boundaries deserve more suspicion than the diagram suggests. The Reference tab is the route into Microsoft's current service documentation. The network will still have opinions. At least they will be evidence-based ones.

Don't Panic — Microsoft Azure Networking

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