3.3 Internet-work Devices

What is the main role of a router?

A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet.

How does a firewall protect a network?

A firewall is a program or device that acts as a barrier to keep destructive elements out of a network or specific computer. Firewalls are configured (in hardware, software, or both) with specific criteria to block or prevent unauthorized access to a network.

How are the physical and logical (network) addresses used when data is routed through an internetwork? Which addresses stay the same? Which addresses change from hop to hop?

Devices such as hubs, switches, and bridges connect multiple devices to the same network segment. Internet-work devices connect multiple networks or subnets together, and enable communication between hosts on different types of networks.

How does a router differ from a switch or a hub?

Routers might have a single WAN port and a single LAN port and are designed to connect an existing LAN hub or switch to a WAN. Ethernet switches and hubs can be connected to a router with multiple PC ports to expand a LAN.