Berkley Software Distribution (BSD) Interview Questions and Answers

Q1. What is BSD (Berkeley Software Distribution) ?
BSD (originally: Berkeley Software Distribution) refers to the particular version of the UNIX operating system that was developed at and distributed from the University of California at Berkeley. “BSD” is customarily preceded by a number indicating the particular distribution level of the BSD system (for example, “4.3 BSD”). BSD UNIX has been popular and many commercial implementations of UNIX systems are based on or include some BSD code

Q2. What Are The Key Objects Oriented Concepts Used By Windows Nt?

• Encapsulation
• Object class
•  instance

Q3.  Is Windows Nt A Full Blown Object Oriented Operating System?
No Windows NT is not so, because its not implemented in object oriented language and the data structures reside within one executive component and are not represented as objects and it does not support object oriented capabilities.

Q4. What Is A Drawback Of Mvt?
It does not have the features like ability to support multiple processors virtual storage source level debugging

Q5. List Out Some Reasons For Process Termination?

• Normal completion
• Time limit exceeded
• Memory unavailable
• Bounds violation
• Protection error
• Arithmetic error
• Time overrun
• I/O failure
• Invalid instruction
• Privileged instruction
• Data misuse
• Operator or OS intervention
• Parent termination.

Q6. What Are The Reasons For Process Suspension?
Reasons for Process Suspension:

• Swapping: OS needs to release some memory
• Other OS reason: suspicion of causing problem or system performance
• Interactive user request: debugging or other resource reasons
• Timing:submit but hold (suspend) a process until another has completed

Q7. Explain the difference between SIGHUP, SIGUSR1 and SIGUSR2?
Those are application specific and therefore are not defined on the OS level.

Q8. What is new in OpenBSD 4.3?
The complete list of changes made to OpenBSD 4.2 to create OpenBSD 4.3 can be found on plus43.html, and highlights on the OpenBSD 4.3 Information page, however here are a few changes the OpenBSD team anticipate will require or warrant some special note to people upgrading or installing OpenBSD 4.3 who are familiar with older versions.

Q9. Why is/is not ProductX included?
People often ask why a particular product is or isn’t included with OpenBSD. The answer is based on two things: the wishes of the developers and compatibility with the goals of the project. A product will not be included simply because it is “neat” — it must also be “free” for use, distribution and modification by our standards. A product must also be stable and secure — a bigger version number does not always mean a better product.

Q10. How do you change your shell to bash?
% chsh -s /usr/local/bin/bash

Q11. Explain the difference between SIGTERM and SIGKILL?
SIGTERM asks the application to terminate in a polite way, it warns about the pending closure and asks the app to finish whatever it is doing. SIGKILL will kill the process no matter what. This is telling the application that it will be shut down no matter what.

Q12. What Design And Management Issues Are Raised By The Existence Of Concurrency?
The operating system must be able to keep track of the various active processes.
The operating system must allocate and de-allocate various resources for each active process.
The operating system must protect the data and physical resources of each process against unintended interference by other processes. This involves techniques that relate to memory, files, and I/O devices.
The results of a process must be independent of the speed at which the execution is carried out relative to the speed of other concurrent process.

Q13. What Are The Contexts In Which Concurrency May Occur?
Concurrency may arise in three different contexts.

1. Multiple applications: -Processing time of the computer to be dynamically shared among a number of active jobs or applications
2. Structured application: – With principles of modular design and structured programming some applications can be effectively implemented as a set of concurrent process.
3. Operating system structure: -The same structuring advantages apply to the system programmer.

Q14.  What Is Fragmentation? Different Types Of Fragmentation?
Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request.
External Fragmentation: External Fragmentation happens when a dynamic memory allocation algorithm allocates some memory and a small piece is left over that cannot be effectively used. If too much external fragmentation occurs, the amount of usable memory is drastically reduced. Total memory space exists to satisfy a request, but it is not contiguous.
Internal Fragmentation: Internal fragmentation is the space wasted inside of allocated memory blocks because of restriction on the allowed sizes of allocated blocks. Allocated memory may be slightly larger than requested memory; this size difference is memory internal to a partition, but not being used

Q15.  What Is The Cause Of Thrashing? How Does The System Detect Thrashing?
Once it detects thrashing, what can the system do to eliminate this problem? – Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of multiprogramming.

Q16. Who maintains OpenBSD?
OpenBSD is maintained by a development team spread across many different countries. The project is coordinated by Theo de Raadt, located in Canada.