Windows Programing Interview Preparation Guide

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A real time operating system has well defined fixed time constraints. Process must be done within the defined constraints or the system will fail. An example is the operating system for a flight control computer or an advanced jet airplane. Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems.Real-Time systems may be either hard or soft real-time.

Hard real-time:
Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM) Conflicts with time-sharing systems, not supported by general-purpose operating systems.

Soft real-time:
► Limited utility in industrial control of robotics
► Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.

Segments can be of different lengths, so it is harder to find a place for a segment in memory than a page. With segmented virtual memory, we get the benefits of virtual memory but we still have to do dynamic storage allocation of physical memory. In order to avoid this, it is possible to combine segmentation and paging into a two-level
virtual memory system. Each segment descriptor points to page table for that segment.This give some of the advantages of paging (easy placement) with some of the advantages of segments (logical division of the program).

Address binding of instructions and data to memory addresses can happen at three different stages
Compile time: If memory location known a priori, absolute code can be generated; must recompile code if starting location changes.
Load time: Must generate relocatable code if memory location is not known at compile time.
Execution time: Binding delayed until run time if the process can be moved during its execution from one memory segment to another. Need hardware support for address maps (e.g., base and limit registers).
Multistep Processing of a User Program

If your process calls a function that creates a kernel object and then your process terminates, the kernel object is not necessarily destroyed. Under most circumstances, the object will be destroyed; but if another process is using the kernel object your process created, the kernel knows not to destroy the object until the other process has stopped using it

The concept of a logical address space that is bound to a separate physical address space is central to proper memory management.
Logical address generated by the CPU; also referred to as virtual address.
Physical address address seen by the memory unit.
Logical and physical addresses are the same in compile-time and load-time address-binding schemes; logical (virtual) and physical addresses differ in execution-time address-binding scheme

To apply the settings of a GPO to the users and computers of a domain, site, or OU, you need to add a link to that GPO. You can add one or more GPO links to each domain, site, or OU by using GPMC. Keep in mind that creating and linking GPOs is a sensitive privilege that should be delegated only to administrators who are trusted and understand Group Policy.

When a process is initialized, the system allocates a handle table for it. This handle table is used only for kernel objects, not for User objects or GDI objects. When a process first initializes, its handle table is empty. Then when a thread in the process calls a function that creates a kernel object, such as CreateFileMapping , the kernel allocates a block of memory for the object and initializes it; the kernel then scans the process?s handle table for an empty entry

Multi programming:
Multiprogramming is the technique of running several programs at a time using timesharing.
It allows a computer to do several things at the same time. Multiprogramming creates logical parallelism.
The concept of multiprogramming is that the operating system keeps several jobs in memory simultaneously. The operating system selects a job from the job pool and starts executing a job, when that job needs to wait for any i/o operations the CPU is switched to another job. So the main idea here is that the CPU is never idle.

Multi tasking:
Multitasking is the logical extension of multiprogramming .The concept of multitasking is quite similar to multiprogramming but difference is that the switching
between jobs occurs so frequently that the users can interact with each program while it is running. This concept is also known as time-sharing systems. A time-shared operating system uses CPU scheduling and multiprogramming to provide each user with a small portion of time-shared system.

Multi threading:
An application typically is implemented as a separate process with several threads of control. In some situations a single application may be required to perform several similar tasks for example a web server accepts client requests for web pages, images, sound, and so forth.

Backing up Active Directory is essential to maintain an Active Directory database. You can back up Active Directory by using the Graphical User Interface (GUI) and command-line tools that the Windows Server 2003 family provides.

You frequently backup the system state data on domain controllers so that you can restore the most current data. By establishing a regular backup schedule, you have a better chance of recovering data when necessary.

To ensure a good backup includes at least the system state data and contents of the system disk, you must be aware of the tombstone lifetime. By default, the tombstone is 60 days. Any backup older than 60 days is not a good backup. Plan to backup at least two domain controllers in each domain, one of at least one backup to enable an authoritative restore of the data when necessary.

GPOs store group policy settings in two locations: a Group Policy container (GPC) (preferred) and a Group Policy template (GPT). The GPC is an Active Directory object that stores version information, status information, and other policy information (for example, application objects).

The GPT is used for file-based data and stores software policy, script, and deployment information. The GPT is located on the system volume folder of the domain controller. A GPO can be associated with one or more Active Directory containers, such as a site, domain, or organizational unit. Multiple containers can be associated with the same GPO, and a single container can have more than one associated GPO.