Explanation/Reference:
Section: Considerations for Expanding an Existing Network Explanation
Explanation:
A hypervisor is a virtual device used to run a guest operating system (OS) within a host OS. A hypervisor is responsible for presenting the physical resources of the host machine as virtualized resources to the guest OS running in a virtual machine (VM). Though VMs share hardware resources with the host OS, they are otherwise isolated from one another. VMs can be used for a variety of purposes, such as software testing or hosting specific network services. An additional programming layer, known as a hypervisor, is required in order for the VM to communicate with the host hardware. A hypervisor is used to allocate hardware resources, such as hard drive space and random access memory (RAM), to the VM.
A virtual switch is a logical device used to allow multiple VMs to communicate within a host system. A VM needs a virtual network interface card (NIC) in order to communicate with other devices. Each virtual NIC is assigned a unique Media Access Control (MAC) address. Similar to a hardware-based switch, a virtual switch maintains a table of MAC-to-port associations. When data is sent from one VM to another, the virtual switch will use this table to determine which port to use to forward the received data. If a virtual switch does not exist on a host, the VM must send data via the physical NIC to a hardware-based switch, where the data can be forwarded to the intended VM.
A virtual router is a logical device used to route packets between VMs and a physical network. A virtual router is a VM dedicated to routing and forwarding packets. For example, the Cisco CSR 1000V is a cloud- based virtual router that is deployed as a VM and managed by a hypervisor. Cisco virtual routers support many of the same features as physical routers and have the added benefit of being able to share resources with other VMs on the host machine.
Hypertext Transfer Protocol (HTTP), not a hypervisor, is used to send documents to a web browser. HTTP is an Open Systems Interconnection (OSI) Application layer protocol that is used throughout the Internet to deliver content from web servers to web browsers, such as Google Chrome or Mozilla Firefox.
Reference:
CCDA 200-310 Official Cert Guide, Chapter 4, Server Virtualization, p. 155