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What's a Network Interface Card (NIC)?

A network interface card (NIC) is the hardware component that connects a device to a network, available in wired, wireless, and server-grade form factors. Understanding NICs also means recognizing how they differ from switch ports, which interconnect devices rather than providing individual network access.

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About this video

A network interface card (NIC) is the hardware component that serves as the interface between a device and the network it connects to. NICs exist in multiple form factors depending on the device and use case. Laptop and desktop machines often have NICs integrated directly into the motherboard, eliminating the need for a separate expansion card, while servers and specialized equipment may use dedicated NIC cards capable of 10-gigabit speeds. Server-grade NICs can also include SFP slots, which accept small form-factor pluggable modules that extend connectivity options to fiber-optic networks using LC connectors. Not all NICs are designed for standard Ethernet. Routers, for example, may use NICs built for older connection types such as T1 lines alongside conventional Ethernet ports. Wireless NICs function on the same principle but transmit and receive data over radio frequencies rather than physical cables, providing network access without a wired connection. A key distinction in networking hardware is the difference between a NIC and a switch port. While a NIC gives a specific device its network identity and handles packet processing, a switch port does not operate the same way. A switch functions at Layer 2 of the OSI model and exists to interconnect multiple devices within the same network, forwarding frames based on MAC addresses without the full packet-processing responsibilities that a NIC-equipped device must handle. This distinction between individual network access and device interconnection is fundamental to understanding how network hardware is designed and classified.

What you'll learn

Identify the function of a network interface card (NIC) and describe how NICs differ across device types, including wired, wireless, and integrated implementations
Distinguish between the role of NICs in end devices and routers versus switch ports in terms of network connectivity and Layer 2 operation

What's covered

Network Interface Cards (NICs)

NIC Types
- 10 Gig Wired NIC
  - Server-based card
  - Four total ports
  - SFP slot support
- Wireless NIC
  - Laptop adapter card
  - Connects to wireless network
- Built-in Motherboard NIC
  - Common in desktops
  - No separate card needed
- T1 NIC Card
  - Used in routers
  - Different from Ethernet
NIC Function
- Device-to-network interface
- Processes network packets
- Operates at Layer 2
SFP Modules
- Slides into NIC port
- Enables fiber connection
- LC fiber connector
Switches vs NICs
- Switch ports not NICs
- Interconnects local devices
- Minimal packet processing
- Layer 2 operation

Aligned to

CompTIA A+ Core 1

2.2 Compare and contrast common networking hardware.

3.4 Given a scenario, install and configure motherboards, central processing units (CPUs), and add-on cards.

Cisco CCST Networking

3.3 Describe endpoint devices.

4.5 Explain basic switching concepts

Cisco CCNA

1.3 Compare physical interface and cabling types

1.1 Explain the role and function of network components

1.13 Describe switching concepts

CompTIA Network+

1.2 Compare and contrast networking appliances, applications, and functions.

Key terms

Network Interface Card: A hardware component that connects a computer to a network.
Media Access Control: A sublayer of the Data Link layer that controls how devices on a network gain access to a medium and transmit data.
Data Link Layer: Layer 2 of the OSI model responsible for node-to-node data transfer and error detection on a single network segment.
Switch: A network device that connects devices within a LAN and forwards traffic based on MAC addresses.
Router: A network device that forwards data packets between networks based on IP addresses.
Small Form-factor Pluggable: A compact hot-swappable transceiver module used in network switches and routers to provide a modular interface for various fiber optic and copper cable types. SFP modules allow the same switch port to be used with different media by swapping the module rather than replacing the hardware.

Transcript

A 10 Gig Network Interface Card

This is a network interface card. It's a 10 gig network interface card that came off of a server that allows me to plug this into a 10 gig network and make connectivity into that network.

It's got four ports total. It has these couple of ports that you can slide in a small form pluggable, or SFP, into and give it extra functionality. So for instance, if I wanted to connect it to a fiber connection, I could slide in an SFP fiber LC fiber connector into there, so I can connect into a fiber network.

Wireless and Built-in NICs

This is a wireless network interface card, so a wireless NIC. This is a card that fits on this laptop to give this laptop some functionality and connect to a wireless system.

It also has a built-in NIC into the motherboard. So even though this is not a separate card, but it is part of the motherboard, we still call it a NIC. And this would allow us to plug into an Ethernet cable just like this. Motherboards for desktop machines typically come with a NIC built into the motherboard, so we don't need to add a separate card in here to be able to connect into the network.

NICs in a Router

This is a router. This has a card that's been slid into it. That's a NIC, a network interface card, for a T1 connection, which is very different than those other ones that I showed you to Ethernet. But it does have two built-in Ethernet NICs in here, so it can connect into a network.

Switch Ports Are Not NICs

This right here is a switch, and it has many ports, but they are not considered NICs. So what is the difference between these ports on this switch and all of those other NICs that I just showed you?

The network interface cards allow these devices to connect to a network. So each one of these devices has a NIC, or several NICs, so it can connect to these different networks.

Now I mentioned that the switch is a little different, because the switch is really not connecting to a network. It's interconnecting all the devices on this network. It operates at that layer 2, so it really doesn't do much processing besides just taking a look at that layer 2 information there, versus the rest of these devices actually have to process the packet. And so it does that through this NIC. It's the interface between the device and the network.

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