TechKnowSurge
CompTIA Network+ 2.1 Cisco CCNA 3.2 Cisco CCST Networking 4.4 CompTIA A+ Core 1 2.2 Cisco CCNA 3.1
TechKnowSurge Catalog Videos What’s a Router?
VideoNetworkFree

What’s a Router?

Routers direct IP packets across networks by examining each packet's destination IP address and determining the most efficient path forward. Unlike switches and hubs that operate at the frame level, routers function as the gateway between a local network and the broader internet.

⚑ Complete this video to capture a CTF flag worth 1 point.

About this video

Routers operate at the network layer and are responsible for directing IP packets between networks, distinguishing them from hubs and switches, which handle data at the frame level within a local area network. When a packet arrives at a router, the device examines the destination IP address and uses that information to select the best next hop — the most efficient path toward the packet's final destination. This decision-making process happens rapidly at each router along the route, with every device passing the packet one step closer to where it needs to go. In a typical network setup, the router sits at the edge of the local area network and serves as the gateway connecting internal devices to external networks, including the internet. Every packet that needs to travel outside the local network is sent to this gateway router first. From there, it moves through a series of intermediate routers, each evaluating the destination address and forwarding the packet accordingly, until it ultimately arrives at its target. The entire routing process is engineered for speed, ensuring that data reaches its destination through the most optimal path available at each step.

What you'll learn

What's covered

Routers & IP Routing

Aligned to

CompTIA Network+
2.1 Explain characteristics of routing technologies.
Cisco CCNA
3.2 Determine how a router makes a forwarding decision by default
3.1 Interpret the components of routing table
Cisco CCST Networking
4.4 Explain basic routing concepts
CompTIA A+ Core 1
2.2 Compare and contrast common networking hardware.

Key terms

Router
A network device that forwards data packets between networks based on IP addresses.
IP Address
A numerical label assigned to each device connected to a network that uses the Internet Protocol.
Packet
A unit of data formatted for transmission over a network, containing a header, payload, and sometimes a trailer.
Default Gateway
The router that a device uses to send traffic to destinations outside its local network.
Hop
A single step in the path a packet takes through the network, specifically the transit from one router to the next closest router toward the destination. The number of hops a packet must travel is used as a routing metric by distance-vector protocols like RIP.

Transcript

We have a hub or a switch that delivers a frame from one location to another. However, what we have for an IP packet is going to be a router. A router routes IP packets. So let's take a look at a router and its function.

The gateway to the world

Here's our local area network, and let's say it's running Ethernet. And at the edge of our network is our router. Our router is the gateway to the rest of the world. And so anything that needs to go out to the rest of the world gets sent to this router, and then this router is going to route that information to where it needs to go.

A router is going to send it where it needs to go based off of the destination IP address. It's going to look at the destination IP address and determine where this packet needs to be sent to.

How packets get routed

Now, what I'd like to do is show you a network of the world with the routers on it and show how it routes across this planet. However, I don't know where all the routers are at, and there would be lots of them. And so really what we're going to do is just take a look at a much smaller network with just four routers on it. So let's look at how packets get routed.

And really, this is built all for speed. So what happens is that a packet comes into a router, and that router is going to take a look at it and say, okay, where does this need to go, and make a determination on what is the next best step that it can take. And so then it will choose the next best route, and then that router will do the same thing and send it to the next one. And then this router will choose, okay, where is the next best route, or this actually needs to go to its destination, and deliver it to its destination.

About TechKnowSurge

TechKnowSurge builds IT and cybersecurity professionals through hands-on, concept-first training built around real understanding — not memorization. Free interactive tools, structured programs, and 25+ years of real-world experience, all in one place.

Explore free tools and programs →