1. In the OSI model, as a data packet moves from the lower to the upper layers, headers are _______
a) Added
b) Removed
c) Rearranged
d) Randomized
Explanation: In OSI reference model, when data packet moves from lower layers to higher layer, headers get removed. Whereas when the data packet moves from higher layer to lower layers, headers are added. These headers contain the essential control information for the protocols used on the specific layer.
2. Which of the following statements can be associated with OSI model?
a) A structured way to discuss and easier update system components
b) One layer may duplicate lower layer functionality
c) Functionality at one layer no way requires information from another layer
d) It is an application specific network model
Explanation: One layer may use the information from another layer, for example timestamp value. The information is contained in the header inserted by the previous layer. The headers are added as the packet moves from higher layers to the lower layers.
3. The physical layer is concerned with ___________
a) bit-by-bit delivery
b) process to process delivery
c) application to application delivery
d) port to port delivery
Explanation: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery or the port to port delivery is dealt in the transport layer. The various transmission mediums aid the physical layer in performing its functions.
4. Which transmission media provides the highest transmission speed in a network?
a) coaxial cable
b) twisted pair cable
c) optical fiber
d) electrical cable
Explanation: Fiber optics is considered to have the highest transmission speed among the all mentioned above. The fiber optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE standard for it is 802.3z. It is popularly used for modern day network connections due to its high transmission rate.
5. Bits can be sent over guided and unguided media as analog signal by ___________
a) digital modulation
b) amplitude modulation
c) frequency modulation
d) phase modulation
Explanation: In analog modulation, digital low frequency baseband signal (digital bit stream) is transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level. The bits are represented by only two frequency levels, one for high and one for low.
6. The portion of physical layer that interfaces with the media access control sublayer is called ___________
a) physical signalling sublayer
b) physical data sublayer
c) physical address sublayer
d) physical transport sublayer
Explanation: The portion of physical layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions. It handles which media connection the signal should be forwarded to physically.
7. The physical layer provides __________
a) mechanical specifications of electrical connectors and cables
b) electrical specification of transmission line signal level
c) specification for IR over optical fiber
d) all of the mentioned
Explanation: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1). Physical layer deals with bit to bit delivery of the data aided by the various transmission mediums.
8. In asynchronous serial communication the physical layer provides ___________
a) start and stop signalling
b) flow control
c) both start & stop signalling and flow control
d) only start signalling
Explanation: In asynchronous serial communication, the communication is not synchronized by clock signal. Instead of a start and stop signaling and flow control method is followed. Unlike asynchronous serial communication, in synchronous serial communication a clock signal is used for communication, so the start and stop method is not really required.
9. The physical layer is responsible for __________
a) line coding
b) channel coding
c) modulation
d) all of the mentioned
Explanation: The physical layer is responsible for line coding, channel coding and modulation that is needed for the transmission of the information. The physical configuration including pins, connectors and the electric current used is dealt in the physical layer based on the requirement of the network application.
10. The physical layer translates logical communication requests from the ______ into hardware specific operations.
a) data link layer
b) network layer
c) trasnport layer
d) application layer
Explanation: Physical layer accepts data or information from the data link layer and converts it into hardware specific operations so as to transfer the message through physical cables. Some examples of the cables used are optical fiber cables, twisted pair cables and co-axial cables.
Why Computer Network ?
The Marvelous Basics: What's the Physical Layer's Gig?
Imagine the Physical Layer as the stagehands of the networking world, making sure your digital show runs smoothly. It's the behind-the-scenes hero, handling the nitty-gritty of actual data transmission.
"Physical" Explained: More Than Just Cables
Before you envision a room filled with endless cables, let's clarify – the Physical Layer isn't just about wires. It's the unsung hero managing the electrical and mechanical bits, ensuring your data dances through the network with finesse.
Cable Chronicles: The Wonders of Transmission
Ever marveled at how your cat videos magically appear on the screen? Thank the Physical Layer for its prowess in transmission. It manages the bits, flips the switches, and voila – entertainment served!
The Bit Bonanza: Binary Banter in the Physical Playground
In the world of 1s and 0s, the Physical Layer is the ultimate binary translator. It takes your digital thoughts and transforms them into the electric language the network understands – a bit like telepathic Morse code!
The Physical Layer's Dance Partners: Devices Galore
Now, imagine the Physical Layer as the ultimate dance floor, and your devices as its lively partners. Whether it's your laptop, smartphone, or even your smart fridge, they all tango with the Physical Layer to make the networking waltz enchanting.
In a Nutshell
The Physical Layer is the unsung hero, the Gandalf of networking, ensuring your data travels the digital highways seamlessly. So, next time you hit send, tip your hat to the behind-the-scenes magician – the Physical Layer! Happy networking, wizards!