Question Bank
What does CSMA/CD stand for?
Carrier Service Multiple Access with Collision Detection
Carrier Sense Multiple Access with Collision Avoidance
Carrier Sense Multiple Access with Collision Detection
Control Sense Multiple Access with Collision Direction
When does a computer send an ARP request?
When it knows the IP address but not the MAC address
After receiving a packet
Before sending an email
During a reboot
What is a VLAN?
Virtual Local Area Network
Visual LAN
Variable LAN
Very Large Area Network
What does a /24 network notation signify?
24 devices in the network
24 networks connected
A subnet mask of 255.255.255.0
24 bits used for the network address
What is a subnet?
A network within the Internet
A smaller segment of a larger network
A network exclusively for submarines
A globally distributed network
How many ports are available in TCP/UDP?
1024
2048
65536
8080
What is port forwarding?
Redirecting traffic from one IP to another
Increasing port speed
Redirecting traffic from one port to another
A security feature to block ports
What is NAT?
Network Address Translation
Network Allocation Table
Network Access Token
New Age Technology
What is the primary purpose of a firewall?
Speed up the network
Translate network addresses
Monitor data usage
Control incoming and outgoing network traffic
What is the maximum length of an IPv6 address?
32 bits
64 bits
128 bits
256 bits
In which topology does each device have exactly two neighbors for communication purposes?
Star
Ring
Mesh
Tree
What causes a running thread to change its state, from Running to Blocked?
any I/O event in the system
starting a new process in the system
terminating the running process
any context switch that happens in the system
When designing an operating system for smartphones and other mobile devices, you should
use bigger page sizes and more states for processes
use smaller page sizes and less states for processes
allow apps to run without interruption from the system, for maximizing user interaction
terminate apps if they run for too long, to avoid starvation of other processes
It is required to use defragmentation in a file system in order to
improve the speed of the context switching in the system
allow smaller seek times for mechanic drives
allow files to be read faster sequentially
reduce boot times for the operating system
Suppose process A has a burst of 5, and starts at moment 0. Process B has a burst of 20, and starts at moment 5. A new process C is created at moment 3, with a burst of 3. Which of the following is true?
in FIFO scheduling, process B runs before process C
in SJF scheduling, process A finishes before C starts
in Round-Robin scheduling (quantum = 3), the first process to execute after A is B
in SRTN (quantum = 3), processes execute as follows: A, C, B, A, B
A 16-bit Von Neumann architecture has a page size of 4,096 bytes and 12 KB of RAM. Access to the pages of the system happen as follows: 5,15,15,5,10. Which of the following is true?
there are 4 physical pages in the system
there are 3 physical pages in the system
there are 16 virtual pages in the system
the FIFO algorithm causes 2 page faults to be issued
in the FIFO algorithm, address 17824 belongs to the first virtual page
Which of the following are true about memory management?
smaller page sizes are favorable when accessing small memory data chunks
larger page sizes are favorable when accessing small memory data chunks
physical addresses usually have a significantly smaller range than virtual addresses
internal memory fragmentation can be resolved by the operating system
external memory fragmentation can be resolved by the operating system
Assume you have a browser tab open in Windows, Linux or MacOS X, where you are playing an YouTube video in 4K (UltraHD) resolution. Which of the following could be true?
the browser tab’s associated thread is more CPU-bound than I/O-bound
the browser tab’s associated thread is more I/O-bound than CPU-bound
the operating system will not schedule any other processes until playback is complete
new processes that are trying to execute during playback are placed in a FIFO waiting queue
interrupts are not allowed during YouTube playback
Assume you are using a Von Neumann system with a CPU that has multiple physical cores. Which of the following is true?
true parallelism can never be achieved through the kernel scheduler, unless the operating system is Linux or MacOS X
true parallelism can never be achieved through the kernel scheduler, unless the operating system is Windows and RAM memory is limited to 4 GB
the kernel can implement true parallelism in a multi-core CPU only if there are no bus limitations
in an interactive system, a pre-emptive scheduling algorithm is required to ensure responsiveness
In a system with a single type of resources, processes A, B and C have a maximum requirement of 10, 20 and 30 resources of type R. An initial allocation is made, of 8, 18, and 28 resources is made for these three processes. Which of the following statements is true?
the minimum number of resources required, so that the state of the system is considered still safe, is 6
the minimum number of resources required, so that the state of the system is considered still safe, is 2
if only 2 resources are available for an additional allocation, the entire system is in a deadlock
an additional allocation of 1 resource to process A will leave the system in a deadlock
You are asked to design a process scheduling mechanism which favors short processes that perform I/O activities, while retaining the system’s interactive requirement, so that the user experience is satisfactory. Which of the following is true?
a preemptive scheduling mechanism is preferred for all interactive systems
a non-preemptive scheduling mechanism is preferred in a situation such as the above
starvation of high-burst processes is possible in certain scenarios
statistically, processes offer the best response times when using the optimum quantum value, instead of higher quantum values
On an interactive operating system, which of the following statements are true:
An user-level process can voluntarily deny pre-emption, to disallow other processes to run.
Page faults happen less often on systems with a high amount of external memory.
It is required to protect critical regions for read accesses, in order to prevent data corruption.
Setting a thread’s priority to a lower level does not impose a guarantee of that thread’s stall in the next scheduler execution cycle.
None of the above.
A system with 1 CPU and 2 cores runs the following 2 threads:
Thread 0:
Thread 1:
If each instruction is atomic, which of the following are possible resulting values for the variables N and M, assuming that initially , ?
(N = 1.5, M = −1)
(N = 1.5, M = −1) or (N = 0.5, M = −1)
(N = 0, M = −1)
(N = 0, M = −2)
none of the above
Assuming you have a system with 1 CPU and 4 cores, and 7 running threads, which of the following statements is true in an interactive operating system:
There will never be more than 4 running threads at once.
The 7 threads are always scheduled in groups of 4 threads running at once.
In a CPU with a superscalar architecture, execution of the threads should be faster overall than on a CPU that is both non-superscalar and non-out-of-order.
You cannot play more than 4 YouTube videos at once on this CPU in this operating system.
All of the above.
A 16-bit system with 16 KB of RAM and a page size of 4 KB has the following page accesses happening in the following order: 0, 1, 1, 0, 2, 1, 2, 0, 1. Which of the following statements are true about this system:
This system has 16 page frames and 4 virtual pages.
This system has 16 virtual pages and 4 page frames.
The sequence of accesses to the pages above causes 3 page faults.
A pointer to an array of 128 characters that points to the address 0x0011 in memory, resides in virtual page number 11.
A pointer to an array of 32 characters that points to the address 0x0016 in memory, resides in virtual page number 0.