A VM in Azure is failing to communicate with other VMs in the same subnet.

Azure normally permits communication among VMs in the same subnet through a default NSG rule that allows intrasubnet traffic. The study guide specifically explains that this connectivity can be broken when an administrator adds an NSG rule that denies the relevant inbound or outbound traffic and therefore overrides the default behavior. Public IP addresses are not required for private communication between VMs located in the same Azure subnet. Regional resource quotas affect resource creation and capacity rather than ordinary packet forwarding among already deployed VMs. User-defined routes can certainly cause routing failures, but the study guide identifies an overridden default NSG rule as a direct cause of VMs in the same subnet being unable to communicate. The administrator should therefore inspect the effective NSG rules and identify any higher-priority deny rule affecting the traffic.