Connecting Network Devices

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If you’re planning on taking the Network+ exam, you should have a basic understanding of network devices that connect clients together.

For example can you answer this question?

Q.  You need to network six PCs together for a basic network. The business owner does not want these devices to access the Internet. Which of the following items do you need? (Select TWO.)

A. Switch

B. Router

C. Firewall

D. CAT6 cables

More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.

Connecting Devices with a Switch

Switches connect devices in a network similar to how hubs connect devices. The primary difference is that switches have more intelligence and make decisions on what traffic to send to each port. Switches make these decisions based on the media access control (MAC) address assigned to each connected device.

A MAC address is a 48-bit address assigned to a client’s NIC and it is typically displayed as six pairs of hexadecimal characters like this 1A-2B-3C-4D-5E-6F or this1A:2B:3C:4D:5E:6F. Valid hexadecimal characters are the numbers 0-9 and the letters A-F. Four bits represent each character. For example, 0001 represents 1 in hexadecimal and 1110 represents E in hexadecimal. If you need to review decimal, hexadecimal, and binary topics, check out this blog post.

You might hear that MAC addresses are unique and are permanently assigned to a NIC. This isn’t exactly correct.

  • MAC addresses are theoretically unique. You are not likely to see any two identical MAC addresses assigned to different NICs, but it is possible.
  • MAC addresses can be changed. MACs are typically burned into the NIC making them semi-permanent. However, you can change the MAC address for the NIC through the operating system or a software tool.

When devices transmit data from one device to another, they include their MAC address as the source MAC address and the other device’s MAC address as the destination MAC address. A switch typically doesn’t know which MAC addresses are associated with each physical port when it is first powered up. However, over time, it tracks the traffic and eventually learns the MAC addresses associated with each of its ports.


Learn more about  the other common network devices.

Sign up for the free Networking Components course here.


As an example, consider the following figure. It shows four computers connected to a basic switch with four ports, and a Port-MAC table created within the switch’s memory. When the switch first turns on, the Port-MAC table is empty. However, when computer A transmits data, the switch captures the MAC address, associates it with port 1, and enters it into the Port-MAC table. At this point, it doesn’t know the MAC addresses for other computers. Over time, the other computers transmit data with their MAC address and the switch populates the Port-MAC table with the captured data.

Network Devices

Basic switch

A switch sends broadcast transmissions to all other ports. However, it evaluates unicast and multicast transmissions and sends them to the destination computers based on the MAC address. For example, if Computer A sends a unicast message to Computer B, the switch sends the data to port 2 of the switch. Computers C and D do not see the data transmission at all.

Remember This

You connect devices together in a network with a hub or a switch. Switches pass all broadcast traffic. They evaluate traffic and forward unicast and multicast traffic based on the destination MAC address.


 

Q.  You need to network six PCs together for a basic network. The business owner does not want these devices to access the Internet. Which of the following items do you need? (Select TWO.)

A. Switch

B. Router

C. Firewall

D. CAT6 cables

Answer are A and D are correct. You would connect the devices with cables (such as CAT6 or CAT5e cables) and a switch.

The business owner doesn’t want the devices to access the Internet so a router or a firewall isn’t needed.

Practice Test Questions To Help You Pass the Network+ Exam (N10-006) The First Time You Take It.

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