Nearly 7,000 TechRepublic members participated in our recent Ethernet networking pop quiz, and the results proved interesting. Overall, participants demonstrated good knowledge of the basics of Ethernet, but a couple of the questions were a little tricky.
To help reinforce your Ethernet knowledge and fill in any gaps you may have on the subject, here’s a look at what lies behind the correct answers to the five-question quiz.
Question 1: CSMA/CD
Most participants knew that the acronym CSMA/CD stands for Carrier Sense Multiple Access with Collision Detection. As its name implies, CSMA/CD provides for collision detection on the network. If two nodes transmit at once, the data gets corrupted. The nodes detect this and continue to transmit for a certain length of time to ensure that all nodes detect the collision. The transmitting nodes then wait for a random time before attempting to retransmit, thus minimizing the chance of another collision.
Collision detection is important on Ethernet networks because only one computer can broadcast at a time. Each computer has to wait its turn, and if two computers attempt to broadcast simultaneously, a collision occurs, necessitating a rebroadcast.
|Most respondents knew what CSMA/CD stands for.|
Question 2: Ethernet specification
Nearly all quiz takers recognized that 802.3 is the IEEE specification for Ethernet as defined by RFC 1042. This specification defined networks using CSMA/CD as a necessary component of Ethernet communications.
However, some members selected IEEE 802.2 as the correct answer. This specification actually defines Logical Link Control (LLC), the upper section of the data link layer for LANs. IEEE 802.11a is a wireless LAN specification, and 802.5 defines a Token Ring.
|802.3 is the IEEE specification for Ethernet|
Question 3: Fast Ethernet connector
The vast majority of respondents to this question knew that RJ-45 is the most common connector used for cat-5 UTP systems. A few thought that the correct answer was FDDI, a network architecture built on fiber optics, or RJ-11, a connector used for standard phone lines. Nobody was fooled by DB-9, a connector used primarily for serial devices on PCs.
|RJ-45 is the standard Ethernet connector.|
Question 4: Star topology
The best answer to the question of which technologies use a star topology is 1000baseT, since it always uses a star topology. But Token Ring (IEEE 802.5) uses a logical ring topology with a physical star topology, so that answer isn’t entirely wrong. As you can see, about a third of respondents made this selection.
CSU/DSU is incorrect; it’s simply the device at each end of a T1 line. And ISDN is a 128K digital dial-up solution that is used for WAN links and Internet access.
|1000baseT is the best answer, but an argument can be made for Token Ring.|
Question 5: Ethernet technologies
When we asked which networking technologies typically use Ethernet, we were talking about the IEEE 802.3 specification used for LAN networking. These two are often used interchangeably, and they are both CSMA/CD specifications—although there are some small differences between them, mostly involving frame format.
10baseT and 100baseTX are two of the primary technologies that currently utilize Ethernet, so those are the two correct answers.
Token Ring has its own specification (802.5); Frame Relay and DS3 are WAN technologies; and FDDI is a fiber technology, which transmits in light rather than over copper, as Ethernet and most other LAN technologies do.
|10baseT and 100baseTX utilize Ethernet.|
These quiz results show that the majority of respondents have a solid understanding of Ethernet basics. Although some of the questions proved a little tricky, many participants zeroed in on the two correct answers for question 5, and overall, the percentage of correct answers was high.
Thanks to everyone who participated in our quiz. We hope it helps you remember some of the important aspects of Ethernet networking. We also hope you’ll find future quizzes both challenging and educational. If you have ideas for quiz topics, post a message in the discussion below.