Understand a server, an IP address and a route.
Several environments on shared hardware
A virtual machine (VM) runs an operating system on virtualised hardware managed by a hypervisor. A container packages an application’s processes and dependencies using operating-system isolation. Containers commonly share a kernel with their host environment; a VM has its own guest kernel.
Both still need networking. A container can have a virtual network interface and an address. Publishing a host port maps access from the host to an application port, depending on the runtime configuration. “The container is running” does not prove that the application listens on the expected address or that a firewall permits it.
Routing table isolation with VRFs
A virtual routing and forwarding instance (VRF) keeps a separate routing context. Two VRFs can use overlapping addresses without automatically connecting them. A VRF is not itself an encryption mechanism. Route sharing between contexts needs deliberate configuration.
In a cloud, a virtual network has its own subnets, routes and policy controls. These abstractions change how resources are created; they do not remove the need to understand addressing or packet paths. Learn the provider-specific rules before assuming every traditional LAN behaviour applies.
Practical exercise
Two isolated routing contexts both contain 10.0.0.0/24. Does identical addressing mean the two networks can communicate?
Show the answer and explanation
No. Addresses have meaning within their routing contexts. Communication requires an intentional connection and appropriate routing and policy; overlaps can complicate that connection.
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