Network Connectivity Problems
Use when the VM is running but unreachable due to Azure network configuration: NSG, routing, NIC, public IP, or DNS.
Symptoms -> Solutions
| Symptom | OS | Action | Docs |
|---|---|---|---|
| no NSG allow for RDP/SSH | Any | Add inbound TCP 3389/22 from approved source | [RDP NSG] |
| NIC and subnet NSGs conflict | Any | Traffic must pass both; inspect effective rules | [Traffic filter] |
| UDR sends traffic to NVA | Any | Check effective routes and NVA forwarding | [Routing] |
| no public IP | Any | Add public IP or use Bastion/private path | [Public IP] |
| guest NIC disabled/down | Windows/Linux | Enable NIC via Run Command or Serial Console | [RDP NIC] / [SSH overview] |
| static guest IP misconfig | Windows/Linux | Restore DHCP guest config | [Reset NIC] / [SSH overview] |
| ghost NIC after disk swap/resize | Windows | Reset network interface | [Reset NIC] |
| DNS failure | Any | Check DNS; Azure default is 168.63.129.16 | [DHCP] |
Quick Commands
bash
az network nic list-effective-nsg --name <nic> -g <rg>
az network nic show-effective-route-table --name <nic> -g <rg> -o table
az vm list-ip-addresses --name <vm> -g <rg> -o table