Exam Power Tips: The OSI layer on CompTIA’s Network+ N10-007 exam with example questions
Updated: 02/21-2021
Why did we make this an “Exam Power Tip”? Because the OSI layer is one of those things you will have to actually memorize! You could get up to 4 – 5 questions on this at the exam (depending on which question bank you get) and unless you remember what layer does what you won’t be able to answer them.
OSI layers fall under “Industry Standards”
On the CompTIA Network plus N10-007 exam, the OSI layer falls under Domain 5: “Industry standards”. OSI which stands for the Open Systems Interconnection model was established by the International Organization for Standardization aka ISO, yes the same three letters as in OSI but that is purely coincidental and has no bearing on anything here except the capacity to get us unnecessarily confused… However, you can now see why this would fall under Domain 5 – “Industry standards”.
The Open Systems Interconnection model (OSI) – First the layers and what they do…
OSI layers 7, 6, & 5
Data and instructions, known as the payload, are generated by an application running on the source host. As an example, the payload can be created by the browser as data passes from the highest layer of the OSI model and down onto the next two layers.
OSI Layer 4 – Transport layer
The Transport layer protocol, typically TCP (for wide area networks or the internet) or UDP (mostly for local area networks) adds a header to the payload. The function of the header is to attach a port number that identifies the application on the destination host. From here on the message, depending on the protocol used, is either a segment or a datagram.
OSI Layer 3 – Network layer
The Network layer adds a header to the segment. That header identifies the IP address of the destination host as well as the message aka a packet.
OSI Layer 2 – Link layer
The packet is passed to the Link layer on the NIC, which encapsulates this data with its own header and trailer, creating what is referred to as a frame. The link layer’s frame includes the physical addresses used to find nodes on the local network.
OSI Layer 1 – Physical layer
This is the Physical layer of the NIC. It receives the frame and places the actual transmission on the network.
A couple of examples of questions that OSI can give rise to at the CompTIA Network+ exam
Which layer of the OSI model is responsible for converting data into signals appropriate for the transmission medium?
- Application
- Physical
- Network
- Data Link
Answer: 2
Explanation: The physical layer’s job is to convert data into impulses that are designed for whatever type of media is being used on the attached segment.
Exam Objective: Main Domain 1: “Networking Concepts”- 1.2 Explain devices, applications, protocols, and services at their appropriate OSI layers.
Segmentation of a data stream happens at which layer of the OSI model?
1. physical
2. Data Link
3. Network
4. Transport
Answer: 4
Explanation: The transport layer receives large data streams from the upper layer and breaks them up into smaller pieces called segments.
Exam Objective: Main Domain 1: “Networking Concepts”- 1.2 Explain devices, applications, protocols, and services at their appropriate OSI layers.
Example of an interactive question out of CertBlaster’s Network+ Practice Test
This is a more comprehensive and complex interactive question from CertBlaster’s Network+ Practice Test for exam N10-007:
The CertBlaster Network+ N10-007 Practice Test suite includes 536 questions because when it comes to practice “quantity IS quality”. The more questions you get the more practice you get and with massive quantities of questions, you will be less likely to apply rote memorization. To find out more about our Network+ practice tests click the button below.
Click here for the full-featured Network+ N10-007 CertBlaster Test Engine
