Post 30 IEEE STANDARDS

IEEE STANDARDS
802.1 Related to Network Architecture
802.2 Defines LLC
802.3 Ethernet
802.4 Token Bus
802.5Token Ring
802.6 MAN
802.7 Broadband LAN using coaxial cable
802.11 wiFi
802.15 Wireless PAN
802.15.1 Bluetooth
Types of CLASSES
CLASS A 0-127 2^7 LAN 2^24 Computers undereach LAN
CLASS B 128-191 2^14 LAN 2^16
CLASS C 192-223 2^21 LAN 2^8
CLASS D 224-239
CLASS E 240-255
CLASS A,B,C are mostly used for unicast communication
CLASS D are used for multicast Communication
PORT NUMBERS
20-FTP data (File Transfer Protocol)
21-FTP Control(File Transfer Protocol)
22-SSH (Secure Shell)
23-Telnet
25 -SMTP(Simple Mail Transfer Protocol)
43-whois
53-DNS (Domain Name Service)
68-DHCP (Dynamic Host Configuration Protocol)
79-Finger
80-HTTP (HyperText Transfer Protocol)
110-POP3 (Post Office Protocol, version 3)
115-SFTP (Secure File Transfer Protocol)
119-NNTP (Network New Transfer Protocol)
123-NTP (Network Time Protocol)
137-NBNS (NetBios naming service)
138-NetBiosDatagram Service
139-NetBIOS Session service
143-IMAP (Internet Message Access Protocol)
161-SNMP (Simple Network Management Protocol)
194-IRC (Internet Relay Chat)
220-IMAP3 (Internet Message Access Protocol 3)
443-SSL (Secure Socket Layer)
445-SMB (NetBIOS over TCP) Server message block
993-SIMAP (Secure Internet Message Access Protocol)
3389-RDP(RemoteDesktop Protocol)

Post 29 OS MCQ

  1. Which of the following is a dynamic scheduling algorithm used in real-time operating systems to place processes in a priority queue?
    A. Earliest deadline first (EDF)
    B. First-Come First-Serve Scheduling(FCFS)
    C. Round Robin Scheduling(RRS)
    D. Multilevel Queue Scheduling(MQS)
    E. None of these
    Answer & Explanation
    A. Earliest deadline first (EDF)
    Explanation:
    Earliest deadline first (EDF) or least time to go is a dynamic scheduling algorithm used in real-time operating systems to place processes in a priority queue.
  2. Which of the following is the module that gives control of the CPU to the process selected by the scheduler?
    A. Device Driver
    B. Scheduler
    C. Dispatcher
    D. All of these
    E. None of these
    Answer & Explanation
    C. Dispatcher
    Explanation:
    The dispatcher is the module that gives control of the CPU to the process selected by the scheduler.
  3. Number of processes completed per unit time is termed as _____
    A. Waiting time
    B. Response time
    C. Turnaround time
    D. Throughput
    E. None of these
    Answer & Explanation
    D. Throughput
    Explanation:
    Number of processes that complete their execution per time unit. 
  4. The time taken in an interactive program from the issuance of a command to the commence of a response to that command is known as?
    A. Waiting time
    B. Response time
    C. Turnaround time
    D. Throughput
    E. None of these
    Answer & Explanation
    B. Response time
    Explanation:
    Response time is the interval between submission of a request.
  5. Which of the following is time required for a particular process to complete, from submission time to completion.?
    A. Waiting time
    B. Response time
    C. Turnaround time
    D. Throughput
    E. None of these
    Answer & Explanation
    C. Turnaround time
    Explanation:
    Turnaround time is the time difference between completion time and arrival time.   
  6. Which of the following is the time difference between turn around time and burst time?
    A. Waiting time
    B. Response time
    C. Arrival Time
    D. Throughput
    E. None of these
    Answer & Explanation
    A. Waiting time
    Explanation:
    An amount of time a process has been waiting in the ready queue.
  7. Which of the following is a time required by a process for CPU execution?
    A. Waiting time
    B. Response time
    C. Arrival Time
    D. Throughput
    E. Burst time
    Answer & Explanation
    E. Burst time
    Explanation:
    Burst time is a time required to complete execution of particular task or process. 
  8. Which of the following is similar to FCFS scheduling?
    A. Earliest deadline first (EDF)
    B. Multilevel Feedback Queue Scheduling(MQS)
    C. Round Robin Scheduling(RRS)
    D. Multilevel Queue Scheduling(MQS)
    E. None of these
    Answer & Explanation
    C. Round Robin Scheduling(RRS)
    Explanation:
    Round robin scheduling is similar to FCFS scheduling, except that CPU bursts are assigned with limits called time quantum.
  9. Which of the following is an example of dynamic priority scheduling algorithms?
    A. Earliest deadline first scheduling
    B. Least slack time scheduling
    C. Round Robin Scheduling(RRS)
    D. Both (A) and (B)
    E. Both (B) and (C)
    Answer & Explanation
    D. Both (A) and (B)
    Explanation:
    Earliest deadline first scheduling and Least slack time scheduling are examples of Dynamic priority scheduling algorithms.
  10. 10.Which of the following is also known as CPU Scheduler?
  11. A. Long Term Scheduler
    B. Short Term Scheduler
    C. Medium Term Scheduler
    D. Both (A) and (B)
    E. Both (B) and (C)
    Answer & Explanation
    B. Short Term Scheduler
    Explanation:
    Short Term Scheduler is also known as CPU Scheduler used to enhance the CPU performance and it runs very frequently

Post No 28 OS MCQ

Multiple Choice Questions On Operating System

1) The collection of processes on the disk that is waiting to be brought into memory for execution forms the ___________ 
1 Ready queue 
2 Device queue 
3 Input queue 
4 Priority queue 
Ans ) 3

2) Demand paged memory allocation 
1 allows the virtual address space to be independent of the physical memory 
2 allows the virtual address space to be a multiple of the physical memory size 
3 allows deadlock tobe detected in paging schemes 
4 is present only in Windows NT 
Ans ) 1 

3) Which is not an Operating System ? 
1 Windows 95 
2 MS-DOS 
3 Windows 3.1 
4 Windows 2000 
Ans ) 3 

4) The operating system manages ________. 
1 Memory 
2 Processor 
3 Disk and I/O devices 
4 All of the above 
Ans ) 4 

5) It is not the layer of the Operating system. 
1 Kernel 
2 Shell 
3 Application program 
4 Critcal Section 
Ans ) 4 

6) ___________ begins at the root and follows a path down to the specified file 
1 Relative path name 
2 Absolute path name 
3 Standalone name 
4 All of the above 
Ans ) 2 

7) Who is called a supervisor of computer acitvity ? 
1 CPU 
2 Operating system 
3 Control unit 
4 Application Program 
Ans ) 2 

8) Consider the two statements. (A) Protection is an internal problem. (B) Security is considered as an external environment within which the system works. Which of the statement is not true? 
1 Only A 
2 Only B 
3 Both A and B 
4 None of the above 
Ans ) 4 

9) The process related to process control, file management, device management, information about system and communication that is requested by any higher level language can be performed by __________. 
1 Editors 
2 Compilers 
3 System Call 
4 Caching 
Ans ) 3 

10) Mutual exclusion 
1 if one process is in a critical region others are excluded 
2 prevents deadlock 
3 requires semaphores to implement 
4 is found only in the Windows NT operating system 
Ans ) 1 

11) Which scheduler controls the degree of multiprogramming? 
1 Short term scheduler 
2 Long term scheduler 
3 Middle term scheduler 
4 None of the above 
Ans ) 2 

12) What is the name of the software which can be legally compiled and often used for free? 
1 Shareware program 
2 Public domain program 
3 Firmware program 
4 Mind Ware 
Ans ) 2 

13) The problem of fragmentation arises in ________. 
1 Static storage allocation 
2 Stack allocation storage 
3 Stack allocation with dynamic binding 
4 Heap allocation 
Ans ) 4 

14) In interactive environments such as time-sharing systems, the primary requirement is to provide reasonably good response time and in general, to share system resources equitably. In such situations, the scheduling algorithm that is most popularly applied is ________. 
1 Shortest Remaining Time Next (SRTN) Scheduling 
2 Priority Based Preemptive Scheduling 
3 Round Robin Scheduling 
4 None of the above 
Ans ) 3 

15) Thrashing occurs ________. 
1 when excessive swapping takes place 
2 when you thrash your computer 
3 whenever deadlock occurs 
4 when no swapping takes place 
Ans ) 1 

16) Boundary registers ________. 
1 Are available in temporary program variable storage 
2 Are only necessary with fixed partitions 
3 Track the beginning and ending the program 
4 Track page boundaries 
Ans ) 3 

17) The principle of locality of reference justifies the use of ________. 
1 Virtual Memory 
2 Interrupts 
3 Main memory 
4 Cache memory 
Ans ) 4 

18) The section of code which accesses shared variables is called as __________. 
1 Critical section 
2 Block 
3 Procedure 
4 Semaphore 
Ans ) 1 

19) Thrashing ________. 
1 Reduces page I/O 
2 Decreases the degree of multiprogramming 
3 Implies excessive page I/O 
4 Improve the system performance 
Ans ) 3 

20) In memory management , a technique called as paging, physical memory is broken into fixed-sized blocks called ___________. 
1 Pages 
2 Frames 
3 Blocks 
4 Segments 
Ans ) 2 

21) The state of a process after it encounters an I/O instruction is __________. 
1 Ready 
2 Blocked/Waiting 
3 Idle 
4 Running 
Ans ) 2 

22) In one of the deadlock prevention methods, impose a total ordering of all resource types, and require that each process requests resources in an increasing order of enumeration. This voilates the _______________ condition of deadlock 
1 Mutual exclusion 
2 Hold and Wait 
3 Circular Wait 
4 No Preemption 
Ans ) 3 

23) Which of the following file name extension suggests that the file is Backup copy of another file ? 
1 TXT 
2 COM 
3 BAS 
4 BAK 
Ans ) 4 

24) The degree of Multiprogramming is controlled by 
1 CPU Scheduler 
2 Context Switching 
3 Long-term Scheduler 
4 Medium term Scheduler 
Ans ) 3 

25) The higher versions of operating systems are so written that programs designed for earlier versions can still be run. What is it called ? 
1 Up gradiability 
2 Upward mobility 
3 Universality 
4 Upward Compatibility 
Ans ) 4 

26) A scheduling algorithm is fair 
1 if no process faces starvation 
2 if a process is starved, detect it and run it with high priority 
3 if it uses semaphores 
4 only if a queue is used for scheduling 
Ans ) 1 

27) A critical region 
1 is a piece of code which only one process executes at a time 
2 is a region prone to deadlock 
3 is a piece of code which only a finite number of processes execute 
4 is found only in Windows NT operation system 
Ans ) 1 

28) Semaphore can be used for solving __________. 
1 Wait & signal 
2 Deadlock 
3 Synchronization 
4 Priority 
Ans ) 3 

29) The operating system of a computer serves as a software interface between the user and the ________. 
1 Hardware 
2 Peripheral 
3 Memory 
4 Screen 
Ans ) 1 

30) What is the name of the software which deals with the running of the actual computer and not with the programming problems? 
1 Operating system 
2 System program 
3 Object program 
4 Source program 
Ans ) 2