1. What are the types of Operating System ?

Ans : Operating system  is a platform between hardware and user which is responsible for the management and coordination of activities and the sharing of the resources of a computer.  It hosts the several applications that run on a computer and handles the operations of computer hardware. There are different types of operating systems. These are as follows:

1. Real-time Operating System: It is a multitasking operating system that aims at executing real-time applications.2. Multi-user and Single-user Operating Systems: The operating systems of this type allow a multiple users to access a computer system concurrently.3. Multi-tasking and Single-tasking Operating Systems:When a single program is allowed to run at a time, the system is grouped under a single-tasking system, while in case the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system.4. Distributed Operating System: An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system.5. Embedded System: The operating systems designed for being used in embedded computer systems are known as embedded operating systems.

2. Give examples of NOS (Network Operating System) and SOS (Server Operating System)

Ans : A networking operating system (NOS), also referred to as the Dialoguer,[1] is the software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions.[2] The network operating system is designed to allow shared file and printer access among multiple computers in a network, typically a local area network (LAN), a private network or to other networks. The most popular network operating systems are Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, and Novell NetWare.

3. Difference between FAT and NTFS

Ans : NTFS is a much more stable format of partion and is the newest. If a NTFS partion becomes corrupt, it can sometimes be recovered with special software. NTFS can also recognize more space on a Hard Drive and is a much more efficient and faster format to use 

FAT is a very old sort of format and goes all the way back to windows 95. It can only recognize a very small hard drives full space. If a FAT partion becomes corrupt then its next to impossible to recover it. A FAT partion has more of a chance of becoming corrupt if your computer crashes. FAT32 is a better version of this format but is still flawed. If EVER offered a choice between FAT and NTFS format then pick NTFS. It will pay off in the future and straight away.

4. Enhancements in Windows 2003 from Windows 2000

5. Enhancements in Windows 2003 from Windows NT

6. What is Active Directory ?

7. Types of Firewall

8. Difference between Hardware and Software Firewall

9. Name the seven layers of OSI model

10. How to enable Firewall in Windows XP

11. How to Disable Firewall in Windows XP

12. Minimum System requirement of Windows XP, Vista, 2003 and 2008

13. Explain ping command

14. Explain Cookies

15. How to boot the computer in Safe mode

16. Types of printer

17. Explain Last Known Good Configuration

18. What is Disk clean up, Disk Defragmentation, Device manager and System Restore

19. USB port Vs Firewire port

20. How to install a printer in Windows XP

21. What is a Browser and name any 5 browsers ?

22. Serial port Vs Parallel port

23. What is a port number ?

24. Where is the HOSTS file located

25. Explain different RAID levels

26. Explain APIPA, IP address and Subnet mask

27. Difference between IP v4 and IP v6

28. How to remove virus from a computer

29. How to make a computer run faster

30. What is attrib command ?31. What is edit command ?32. How to copy a file or folder using copy command33. How to format the hard disk using command line utilities

34. Explain mkdir, rmdir and chdir commands35. Types of hard disk

36. Difference between primary and secondary partition

37. Types of backups in Window OS

38. Differential Backup Vs Incremental Backup Vs Copy backup

Ans:-

39. What is remote desktop.

Ans:-Remote desktop is a program or an operating system feature that allows the user to connect to a computer in another location, see that computer's desktop and interact with it as if it were local.People use remote desktop capability to do a variety of things remotely, including the following:

Access a workplace computer from home or when traveling. Access a home computer from other locations. Fix a computer problem. Perform administrative tasks. Demonstrate something, such as a process or a software application.

40. Recovery Console Vs Automated System Recovery

41. What is NTLDR file

Ans:-The NTLDR file is an essential part of the boot process in Windows NT/2000/XP. NTLDR stands for NT Loader, which is the boot loader for all three of these operating systems. If the NTLDR file is damaged or missing, the boot process cannot complete. This makes it a crucial part of the boot process because one of its functions is to load the operating system and drivers

42. How to tackle "missing NTLDR file" error

Ans:- There are so many causes for this error and most common are following 1 Computer is booting from a non-bootable media. 2 Computer BIOS Setting is not proper for hard disk drive 3 Misconfiguration with the boot.ini file. 4 Corrupt NTLDR and/or NTDETECT.COM file 5 Corrupt boot sector / master boot record 6 Virus infections, human errors, power outages

43. How many bytes are there in MAC address

Ans:-

A Mac address is a 48bit addressing scheme (usually represented in HEX). There are 8 bits in a bytes therefore it is 6 bytes long.

44. Range of Class A,B,C,D,E IP address

Ans:-Class Address Range Supports

Class A 1.0.0.1 to 126.255.255.254 Supports 16 million hosts on each of 127 networks.

Class B 128.1.0.1 to 191.255.255.254 Supports 65,000 hosts on each of 16,000 networks.

Class C 192.0.1.1 to 223.255.254.254 Supports 254 hosts on each of 2 million networks.

Class D 224.0.0.0 to 239.255.255.255 Reserved for multicast groups.

Class E 240.0.0.0 to 254.255.255.254 Reserved.

45. Default subnet mask of Class A, Class B and Class C IP address

Ans:-

IP Default Subnet Masks For Address Classes A, B and C

Subnetting is the process of dividing a Class A, B or C network into subnets, as we've seen in the preceding topics. In order to better understand how this “division of the whole” is accomplished, it's worth starting with a look at how the “whole” class A, B and C networks are represented in a subnetted environment. This is also of value because there are situations where you may need to define an unsubnetted network using subnetting notation.

This might seem like a strange concept—if you aren't going to bother creating subnets, why do you need to consider how the old-fashioned classes are used under subnetting? The answer is that after subnetting became popular, most operating systems and networking hardware and software were designed under the assumption that subnetting would be used. Even if you decide not to subnet, you may need to express your unsubnetted network using a subnet mask.

In essence, a non-subnetted class A, B or C network can be considered the “default case” of the more general, custom-subnetted network. Specifically, it is the case where we choose to divide the host ID so that zero bits are used for the subnet ID and all the bits are used for the host ID. I realize that this seems like a bit of a semantic game. However, this default case is the basis for the more practical subnetting we will examine in the next topic.

Just as is always the case, the subnet mask for a default, unsubnetted class A, B or C network has ones for each bit that is used for network ID or subnet ID, and zeroes for the host ID bits. Of course, we just said we aren't subnetting, so there are no subnet ID bits! Thus, the subnet mask for this default case has 1s for the network ID portion and 0s for the host ID portion. This is called the default subnet mask for each of the IP address classes.

Since classes A, B and C divide the network ID from the host ID on octet boundaries, the subnet mask will always have all ones or all zeroes in an octet. Therefore, the default subnet masks will always have 255s or 0s when expressed in decimal notation. Table 51 summarizes the default subnet masks for each of the classes; they are also shown graphically in Figure 68.

Table 51: Default Subnet Masks for Class A, Class B and Class C Networks

IP Address Class

Total # Of Bits For Network ID / Host ID

Default Subnet Mask

First OctetSecond Octet

Third Octet

Fourth Octet

Class A 8 / 2411111111

(255)00000000

(0)00000000

(0)00000000

(0)

Class B 16 / 1611111111

(255)11111111

(255)00000000

(0)00000000

(0)

Class C 24 / 811111111

(255)11111111

(255)11111111

(255)00000000

(0)

 

Figure 68: Default Subnet Masks for Class A, Class B and Class C Networks

So, the three default subnet masks are 255.0.0.0 for Class A, 255.255.0.0 for class B, and 255.255.255.0 for Class C. Note that while all default subnet masks use only “255” and “0”, not all subnet masks with “255” and “0” are defaults. There are a small number of custom subnets that divide on octet boundaries as well. These are:

o 255.255.0.0:,This is the default mask for Class B, but can also be the custom subnet mask for dividing a Class A network using 8 bits for the subnet ID (leaving 16 bits for the host ID).

o 255.255.255.0: This is the default subnet mask for Class C, but can be a custom Class A with 16 bits for the subnet ID or a Class B with 8 bits for the subnet ID.

Key Concept: Each of the three IP unicast/broadcast address classes, A, B and C, has a default subnet mask defined that has a one for each bit of the class’s network ID, a zero bit for each bit of its host ID, and no subnet ID bits. The three default subnet masks are

255.0.0.0 for Class A, 255.255.0.0 for class B, and 255.255.255.0 for Class C.

46. What is BSOD (Blue Screen of Death) and how to overcome it

Ans:-

Anyone using Windows has likely experienced the infamous Blue Screen of Death (BSOD).

This is a common error that occurs whenever windows senses a software, hardware, or

driver error preventing it from operating properly. So basically, almost anything from a

minor glitch to a major system malfunction can cause this error to appear. Sometimes this

problem will go away with a simple reboot and you may never see the blue screen again.

But more typically, the Blue Screen of Death (BSOD) is an indication of something serious

and it will not simply go away. In terms of how to fix the Blue Screen of Death, there is no

simple answer to that. Fixing it means first diagnosing the problem to find out what is wrong

with your PC.

The first thing to do to analyze a blue screen error is to check the meaning of the STOP error

code. You need to stop Windows from rebooting when a STOP error is encountered. Once the

blue screen of death is shown, you can check the meaning of the STOP error code. Together

with the filename of the driver or module, this will give an indication of the error cause.

Another option to analyze the cause of the blue screen error is to look at the Windows

system event log or to debug the memory dump (minidump) that Windows created when

the error occurred. The event log can be viewed using the event viewer. Right-click

Computer in the Start menu, and then select Manage. In the Computer Management window

select Event Viewer. The information in the event log can be of great help to isolate the

cause of the blue screen error.

In reality, the most common cause of blue screen errors is a device driver problem.

Outdated, incorrect or corrupt drivers can cause the system to encounter a STOP error,

resulting in the BSOD. So the easiest way to try and fix a blue screen error is to reinstall and

update your system’s device drivers. This will ensure that all driver bugs are fixed and that

all hardware has the correct driver.

If you know which device caused the error, you can update or reinstall that driver first. The

file name in the blue screen of death can help identify the driver. Look for a file with the .SYS

extension and search for that file name. If you do not have the drivers for all devices, or are

not comfortable updating your PC’s drivers manually, you can use a driver update tool to

find, download and update all device drivers for you. Such tools will accurately identify your

computer hardware, including any device causing an error, and automatically install the

latest drivers for it. In most cases updating or reinstalling drivers will solve your blue screen

errors.

However, if updating device drivers does not fix the blue screen error, there are a number of

additional things to try:

* Load the default BIOS values – resource conflicts and timing issues can be caused by

incorrect BIOS settings.

* Update the BIOS – especially after adding new hardware or installing a Windows service

pack this can help fix issues.

* Update Windows – missing updates, including service packs can be a source of stop errors.

* Check your system – run a virus scan and spyware scan after updating your definition files.

* Driver rollback – if you have recently updated a driver, you can use the driver rollback to

revert back to the previous driver version.

List of STOP Errors Causing BSOD:

* Stop 0×00000003 UNSYNCHRONIZED_ACCESS

* Stop 0x0000000A IRQL_NOT_LESS_OR_EQUAL

* Stop 0x0000001E KMODE_EXCEPTION_NOT_HANDLED

* Stop 0×00000023 FAT_FILE_SYSTEM

* Stop 0×00000024 NTFS_FILE_SYSTEM

* Stop 0x0000002E DATA_BUS_ERROR

* Stop 0x0000003F NO_MORE_SYSTEM_PTES

* Stop 0×00000044 MULTIPLE_IRP_COMPLETE_REQUESTS

Here’s some tips on how to fix a BSOD :

1. Check the condition of Computers in General

Before doing further troubleshooting, the first step we should do is check the condition of

computers in general, include the following:

· Check the cleanliness inside the CPU casing. Clean dust and other impurities could

premises brush and vacuum cleaner, if necessary, prepare the electrical contact cleaner to

clean the motherboard.

· Check the condition of the temperature of each component such as Power Supply (make

sure the fan rotates normally), VGA card and processor heatsink.

· Ensure that the various components (such as RAM, VGA Card, connector IDE / SATA

connector Power Supply, etc.) are installed properly, to make sure they can pull out and put

it back.

· If you recently install new hardware components (eg VGA Card), unplug wrote first and try

running the computer once wrote that the causes Bluescreen.

2. Use the Safe Mode

The next step is to run Windows in Mode “Safe Mode” which is one of the options on the

Advanced Boot Options menu of Windows XP by pressing repeatedly the F8 key during

startup the system will perform. After Windows managed to get into Safe Mode, do some

troubleshooting the following:

· Clean the hard drive of your antivirus, spyware mallware & program by running a virus

scanner.

· Uninstall Driver problematic, the way to go to Computer Management window click on

Device Manager and look for any sign components that thrill, or driver components recently

installed or updated.

· If you need to first uninstall the antivirus program installed, if conditions are normal

conditions in the computer can be installed again and make sure the database engine-ya is

always up to date.

· We can also use the utility “System Restore” to restore the computer settings to an earlier

time. Click on Start, All Programs, Accessories, System Tools, System Restore.

3. Check the computer’s conditions

Conditions are bad hard drive can also result in a bluescreen, so check the hard drive by

running CHKDSK. Run a defragmentation program also Hardisk to ensure hard work

optimally.

4. Check the RAM Condition

Check the condition of the memory / RAM, make sure have been installed correctly, and run

the program weeks to check the condition of memory such as “Windows Memory

Diagnostic”

5. Repair Windows Operating System

Sometimes the bluescreen happens because there are some Windows files are corrupted, to

resolve the most easy way is to do a Repair on the Windows operating system is your

favorite

6. Use tools to analyze the cause of occurrence of bluescreen

Look for dump file on a computer hard drive that experienced bluescreen, usually in C: \

WINDOWS \ minidump and copy to your computer and run applications WhoCrashed or

BlueScreenView to find the causes bluescreen.

47. Difference between Preferred DNS and Alternate DNS server

Ans:-

Default Gateway - In a network using subnets, the router that forwards traffic to a destination outside of the subnet of the transmitting device. 

Subnet mask - used to determine what subnet an IP address belongs to. An IP address has two components, the network address and the host address. For example, consider the IP address 150.215.017.009. Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network. 

Preferred and Alternate DNS server - This is a server that translates domain   names  into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain   name , therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4. The DNS system is, in fact, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned. So, it will check the "Preferred" DNS server first, if it can't translate the name, then it will hit the "Alternate" DNS server.

50. Transmission speed of T1 carrier

Ans:-

Transmission speed of T1 carrier

T1, T1c, T2, T3, T4

T(n) Quick OverviewSome Electrical Characteristics for Tn

Cabling co-directionalMark 3.0 VdcSpace 0 Vdc +/- 0.30 VdcPulse width 648 ns +/- 15 ns

Encoding AMI (bipolar) and B8ZS

Speed

T1: 1544 kbps +/- 50 ppmT1c: 3152 kbps +/- 50 ppmT2: 6312 kbps +/- 50 ppmT3: 44736 kbps +/- 50 ppmT4: 274760 kbps +/- 50 ppm

Description

The T1 (trunk) digital lines were developed to replace the analog lines that interconnected the local telephone offices (CO, central office) in the USA. The CO's were connected using 4-wire lines, and frequency division multiplexing to get enough bandwidth to handle enough calls between local offices. Each call was allocated 3kHz of bandwidth, 0-3, 3-6, 6-9, etc. on the trunk line. Because of the variation with time and temperature of the characteristics of the discrete components used, these lines needed a lot of maintenance and still were not free of cross talk due to overlapping bands. Every 1830m/ 6000ft an amplifier was needed that also amplified noise. T1 was decided to sample a 4kHz bandswidth at an 8k (2x highest frequency) sample rate taking 8 bit samples. That resulted in a 64kbps digital signal. Combining 24 channels results in 1.536Mbps. Adding a framing bit gives the 1.544Mbps that T1 is known for. The old analog amplifiers were replaced by T1 repeaters or digital regenerators. The digital signal was regenerated not amplified, thus discarding any noise that was picked up.The T1 trunk lines are changed over now to carry the ISDN network signals. The 2B+D Basic Rate Interface uses 64k for each B-channel plus 16k for the D-channel, the 23B+D Primary Rate Interface uses 64k for each B-channel plus 64k for the D-channel, which equals 1.544 Mbps, T1 bandwidth. The PRI in Europe uses 31B+D because the 2.048Mbps E1 lines there allow for 32 64k channels.

How they invented the speedsT1 and up is the terminology for digital, two-way transmission of voice, data, or video over a single highspeed circuit. The transmission rate is based on the bandwidth for one voice channel in digital form. This channel is called DS-0 and consists of 64 kbps of bandwidth.By Time Division Multiplexing 24 DS-0 channels, T1 is formed. But there is more. To separate the different channels a framing bit is used. For framing 8000 bps are used.T1 gives you 24 analog voice channels plus the framing rate. This makes the T1 speed: 24 x 64000 + 8000 = 1.544 Mbps. For the other T-versions an equal equasion is used ending everything up to the specs given in the table below.

Carrier Signal Level # of T1 signals # of Voice Channels Speed

T1 DS-1 1 24 1544 kbps

T1c DS-1c 2 48 3152 kbps

T2 DS-2 4 96 6312 kbps

T3 DS-3 28 672 44736 kbps

T4 DS-4 168 4032 274760 kbps

The DS-1 interfaceThere are several different possible interfaces for T1. For copper the DS-1 interface can transmit signals 1828 meter (6000 feet) over 24 AWG twisted pair cable. The actual connectors are a Sub-D15 female or a RJ45 female.

Sub-D15 Female RJ45 Female

Sub-D15 RJ45 Signal

1 5 Transmit Tip

3 2 Receive Tip

9 4 Transmit Ring

11 1 Receive Ring

2 and 7 7 and 8 Ground

FramingFor a receiving multiplexer to recognize what is what in the incoming bitstream some smart things are done. First of all from every channel only 8 bits at a time are send. Each of those 8 bits is called a time slot, so T1 consists of 24 time slots in the frame. The entire frame is thus 192 (24 x 8) bits and 1 control bit (the framing bit) which makes up 193 bits in total. At a repeat speed of 8000 times per second you get the T1 rate of 1.544 Mbps.The modern T1 lines use one of two framing schemes: SuperFrame (SF) or Extended SuperFrame (ESF).

SF

Also known as D3/D4 frame (CCITT: G.733). Each superframe consists of 12 frames. The 193rd bit has different meanings. In the odd-numbered frames it acts as a terminal framing bit (FT), but in the even-numbered frames it acts as a signaling framing bit (FS).FT frames are used for synchronization.FS frames may be used for synchronization or for data link communication between terminals or in SLC-96 applications.The framing bits (FT and FS togather) have a sequence of 1000 1101 1100. One out of 8 bits is robbed for signaling from each DS-0 through DS-24 channel in the 6th and 12th frame of each superframe. This way of bit robbing is refered to as A/B signaling: 2 bit codes for on-hook, off-hook, busy or idle.

FrameNumber

FT FSInformation

bitsSignaling

bitSignalingchannel

1 1 - 1-8    2 - 0 1-8    3 0 - 1-8    4 - 0 1-8    5 1 - 1-8    6 - 1 1-7 8 A7 0 - 1-8    8 - 1 1-8    9 1 - 1-8    10 - 1 1-8    11 0 - 1-8    12 - 0 1-7 8 B

ESFAlso known as D5 frame or Fe. Each extended superframe consists of 24 frames. The ESF knows 3 different framing types:Synchronization: bit sequence 001011 in frames 4, 8, 12, 16, 20, 24Data Link: frames 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23CRC-6: frames 2, 6, 10, 14, 18, 22One of 8 bits of each DS-0 channel is robbed for signaling in 6th, 12th, 18th, and 24th frame. This is also called A/B/C/D signaling. The options define up to 16 features.6 out of 24 S-bits are used for synchronization. The are called Fe bits. The remaining bits are used for a 4 kbps data link and an ESF block check as shown in the table below.

FrameNumber

S-bits Bit use in eachchannel time slot

Signaling-bitUse options

Fe DL CRC Traffic Signaling T 2 4 161 - m - 1-8          2 - - C1 1-8          3 - m - 1-8          4 0 - - 1-8          5 - m - 1-8          6 - - C2 1-7 8 - A A A7 - m - 1-8          8 0 - - 1-8          9 - m - 1-8          10 - - C3 1-8          11 - m - 1-8          12 1 - - 1-7 8 - A B B13 - m - 1-8          14 - - C4 1-8          15 - m - 1-8          16 0 - - 1-8          17 - m - 1-8          18 - - C5 1-7 8 - A A C19 - m - 1-8          20 1 - - 1-8          21 - m - 1-8          22 - - C6 1-8          23 - m - 1-8          24 1 - - 1-7 8 - A B D

This way only 25% of the 8000-bit bandwidth for frame synchronization, 2 kbps is used for framing, 2 kbps is used for error checking and 4 kbps is used for diagnostics and performance characteristics, which is called the Facility Data Link.