A network is experiencing a number of CRC errors during normal network communication. At which of the following layers of the OSI model will the administrator
MOST likely start to troubleshoot?
A network is experiencing a number of CRC errors during normal network communication. At which of the following layers of the OSI model will the administrator
MOST likely start to troubleshoot?
A network experiencing CRC errors indicates issues at the Data Link Layer, which is Layer 2 of the OSI model. Cyclic Redundancy Check (CRC) is a method used for error-checking in frames, which are the protocol data units at Layer 2. Because CRC errors pertain to how data is formatted and transmitted over a network segment (often related to the error-detection data in the frame's trailer), it would be most appropriate to start troubleshooting at Layer 2.
The data unit on Layer 2 is a frame. Each frame contains a frame header, body, and a frame trailer: Header: typically includes MAC addresses for the source and destination nodes. Body: consists of the bits being transmitted. Trailer: includes error detection information. When errors are detected, and depending on the implementation or configuration of a network or protocol, frames may be discarded or the error may be reported up to higher layers for further error correction. Examples of error detection mechanisms: Cyclic Redundancy Check (CRC) and Frame Check Sequence (FCS). Learn more about error detection techniques here. Answer is Layer 2 (B)
I had this on my exam, and I answered A. Now, I believe that's incorrect in light of my score report, which included this objective: "1.1 Compare and contrast the Open Systems Interconnection (OSI) model layers and encapsulation concepts." I'm all but 100% certain it's because I misanswered this, which is the only OSI-related question I can remember. B is most likely the correct answer. CompTIA's rationale? I'll try to guess. First step in the troubleshooting methodology is to identify the problem. You would probably have to start at Layer 2 for the "identify symptoms" substep, where you'd check the CRC errors themselves on a data-link interface You wouldn't go to Layer 1 until step 2, when you "establish a theory of probable cause." Most likely the technician would theorize physical (cabling) issues and test it accordingly, but that's not during the FIRST troubleshooting step.
I agree with you. The question doesn’t ask where the problem is located. It asks where you’d start trouble shooting. Why would anyone start messing with cables before analyzing the data that would give them more information on what’s causing it?
CRC IS L2
Ethernet frame CRC (FCS) is usually understood to be on OSI layer 2
I would agree with B on this one. Other sites also saying B is the correct answer.
Changed my mind to A. Administrator would START troubleshooting at Layer 1 first.
The CRC errors typically indicate issues at the physical layer (Layer 1) of the OSI model, so the administrator would likely start troubleshooting there. Therefore, the correct answer is A. Layer 1.
In summary, while CRC is useful for local error detection within a single hop (e.g., within a LAN segment), it doesn’t cover end-to-end communication. Each layer’s specific checks serve different purposes, ensuring robustness and reliability throughout the network. Therefore, starting troubleshooting at Layer 1 is the most logical approach
CRC errors typically occur at Layer 1 of the OSI model, which is the physical layer responsible for transmitting raw binary data over the network medium. CRC errors indicate issues such as faulty cabling, loose connections, electromagnetic interference, or problems with network interface cards (NICs). Therefore, the administrator would begin troubleshooting at Layer 1 to address these physical layer issues.
Cyclic Redundancy Check is a powerful algorithm that is used for error control in the data link layer. The number of 0 bits appended on the sender's side is equal to the highest number of polynomial degrees.
CRC (Cyclic Redundancy Check): It's an error-detection mechanism used at Layer 2 (Data Link Layer) to ensure data integrity during transmission. Layer 1 Involvement: However, CRC errors often indicate underlying physical layer issues, such as: Faulty cables Loose connections Interference Hardware defects
7. Application Layer 6. Presentation Layer 5. Session Layer 4. Transport Layer 3. Network Layer 2. Datalink Layer (Sender and receiver info mismatch) 1. Physical Layer
Its B because the data unit on Layer 2 is a frame.
There is normal network communication in progress going on, this means you would only be able to troubleshoot layer 2 without causing interference. If there is not normal network communications going on, you can check the layer 1 cables, ports & transceivers.
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tbh idk i just guessed
CRC-4 checks for data transmission errors on E1 trunk lines at the data link layer (Layer 2) or transport layer (Layer 4) of the OSI model for how applications communicate over a network. An error is said to have occurred when there is a mismatch between the receiver's information and the sender's information, thus involving the frames. https://www.techtarget.com/searchnetworking/definition/CRC-4#:~:text=CRC%2D4%20checks%20for%20data,information%20and%20the%20sender's%20information. Syslog uses layer 4 UDP diagnostics to check layer 2 frames to ensure they are sent correctly. Layer 3 would be putting them into packets to ensure they are sent to the correct location.