CompTIA® A+ Essentials Exam Notes : SCSI termination, DOS format and IPA cleaning

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31)IDE (or EIDE or ATA or PATA), and SATA are two most commonly used interface standards for connecting to the internal hard drives. SCSI is another standard most commonly used when connecting hard drives in a Server computer.

32)If Autoexec.bat tried to access a drive letter that is not valid, the error message "Current drive is no longer valid" appears.

33)If is possible that a customer could not explain the problem clearly on phone. Best way is to seek additional help as required.

34)If the CMOS setup is not properly setup the computer may ignore or not look at the CD-ROM as a bootable option. Verify in the CMOS that your settings are properly set to boot from the CD-ROM drive.

Generally, these settings will be under the boot options. Setup your boot options similar to the below example.

1 - Floppy / LS120

2 - CD-ROM

3 - Network (if available)

4 - Hard Disk Drive

If CD-ROM is listed after a device that is bootable it will boot from the other device before the CD-ROM. Verify that the devices before CD-ROM, such as floppy, do not have bootable media in them.

35)If the termination is not done, a SCSI devices on the bus will not function properly. This is due to reflection of the signals at the end of the bus. To prevent this, both ends of the SCSI bus need to be terminated. If one end of the SCSI bus is terminated, you may find intermittent problems. Never terminate the bus at a device connected in between.

If you are getting a keyboard error, you need to do one of the following things:

1. Check if the keyboard needs to be cleaned

2. Check if the keyboard cable has become loose

3. Check if one or more of the keys are stuck

4. If required, replace the keyboard.

36)If you do not know the voltage across any two points, set the voltage range in the voltmeter to the largest possible number and reduce gradually.

If you fail to boot, first try to boot in Safe Mode. If it doesn't work, try booting to Last Known Good Configuration. If both fail, you can try using Recovery Console.

37)If you have a standard desktop PC that uses integrated drive electronics (IDE) disk drives, then these will be detected during setup. If, however, you use SCSI disks or have Redundant Array of Independent Disk (RAID) storage systems, you will see, shortly after the reboot, the following line of text displayed at the bottom of the screen:

"Press F6 if you need to install a third party SCSI or RAID driver..."

Pressing F6 will start a dialog that allows you to configure and install the drivers for your SCSI or other disk subsystem controllers. This option is usually used on server platforms that use large-capacity, high-speed, fault-tolerant disk subsystems. For most PCs, however, you won't need to use this option.

38)If you notice that the time is constantly incorrect, even after adjusting correctly, the most likely cause is that the CMOS battery has become weak and need to be replaced.

If you want to format a drive and also make it bootable, you need to format with /s switch. By issuing this command, the boot files IO.SYS, MSDOS.SYS, COMMAND.COM get copied to the disk.

If your Microsoft Windows XP-based computer does not start correctly or if it does not start at all, you can use the Windows Recovery Console to help you recover your system software.

Automated System Recovery (ASR) is a part of an overall plan for system recovery so that you are prepared if the system fails. ASR should be a last resort for system recovery. Use ASR only after you have exhausted other options. It is recommended that you use ASR only if all other options to repair the system (such as Last Known Good, and Safe Boot) have failed.

39)Impact printers are capable of printing multipart forms, since they can give necessary impression to print to multiple forms simultaneously.

In an EP process:

1. The transfer corona has positive charge

2. The primary corona has negative charge

3. The toner will have negative charge

InkJet is the generic name given for contactless printing using ink. BubbleJet and DeskJet are the names of Cannon and HP InkJet printers respectively.

Internet is based on TCP/IP protocol. TCP/IP is the medium of transport when your are accessing the Internet.

IPCONFIG gives the current IP address asigned to the Windows 2000 computer.

ipconfig/all provides the MAC address of your computer.

40)IsoPropyl Alcohol (IPA) is recommended for cleaning PCAs such as motherboards. Mild detergent can be used for cleaning the outside cabinet or the keyboard.

It is important that you consult manufacturer's documentation before starting any preventive maintenance or cleaning operation. Usually, manufacturers provide proper cleaning methods and the solvents / tools to be used for this purpose.

It is important that you do not make the issue personal. Maintain professional approach, and try to resolve the problem for which you had been called.

It is important to know that ESD damage may not be known immediately. A component may only suffer degradation in performance, which may show up only at a later date. In some cases, an ESD may result in the failure of the component instantly.

It is important to know that the ends of a SCSI chain need to be terminated. There are 3 configurations possible:

1. The SCSI host adapter and only internal SCSI devices

2. The SCSI host adapter and only external SCSI devices

3. The SCSI host adapter and both internal and external devices on the same SCSI segment.

In case 1, and case 2 the SCSI host adapter and the extreme end device need to be terminated. In case 3, the SCSI adapter usually sits some where in between the internal and external devices, and hence should not be terminated. Only the end devices (i.e. one at the end of the internal SCSI segment, and one at the end of the external SCSI segment) need to be terminated. Note that the devices that are not at the extreme ends of the SCSI chain should not be terminated. For any given SCSI segment, only two devices (that are at the ends) should be terminated.

41)It is recommended that the backup tape is stored at a location away from the building where the backup was taken. For most companies, backups contain important data and loosing backups may affect the continuity of one's business. If a backup is stored in the same building, it may get damaged in fire or any other natural calamities along with the computers. As a result, both the server, as well as back fail at the same time. Therefore, it is recommended to store the backup at a different location.

It is very important that you verify that the backup is working properly. It may so happen that you have several backup tapes, but none of them is good!

42)It is recommended that you clean the LCD screen with clean water, using a soft cotton cloth. Do not spray water directly on the screen. First wet the cloth (no dripping of water), and wipe the LCD screen gently.

Key boards come with two types of connectors. They are:

3. DIN-5

4. Mini DIN-6

DIN-5 are used with AT style keyboards. DIN-5 has 5 pins. Mini DIN-6, also known as PS/2 connector has a round port with 6 pins, one of which being a square pin used for alignment.

LAN: Local Area Network

WAN: Wide Area Network

MAN: Metropolitan Area Network

Laptop batteries (and most other batteries) consist of hazardous material. You need to dispose them according to the hazardous material disposal procedures. Enquire local authorities about disposal procedure.

43)Level 1 cache is internal to the processor, and level 2 cache is external to the processor, it resides on the motherboard. In case of Pentium II, L2 cache is built into the catridge.

Liquid Crystal Technology is most commonly used for laptop displays.

Low level formatting will erase the data on a hard drive permanently.

MAC limiting the MAC addresses that can access the wireless network, you can prevent unauthorized computers from accessing your wireless network. Note that each MAC address is unique, and hence MAC address filtering can effectively prevent unauthorized computer access.

Machines running Windows 9X can be grouped together to share network resources. This type of network is called peer-to-peer network. The name comes from the fact that all the computers on the network are considered as equal partners or peers.

Microsoft Internet Explorer and Windows Explorer can be used for assigning Share and NTFS permissions on a Windows 2000 computer.

44)Most Baby-AT type motherboards were manufactured until 1998. ATX motherboards have the processor at the rear end of the motherboard and out of the way of expansion cards (unlike AT / Baby AT boards). In addition, ATX form integrates the serial and parallel ports on the motherboard.

Most commonly, the devices that support SCSI include the following:

1. Hard drives

2. Tape drives

3. CD ROM drives

MSDS stands for Material Safety Data Sheet. It is US state department document that contain information on any substance that is hazardous, and proper use / disposal.

45)NBTSTAT This utility displays current NetBIOS over TCP/IP connections, and display NetBIOS name cache.

NETSTAT Displays protocol statistics and current TCP/IP connections since the server was last booted.

TRACERT Used to determine which route a packet takes to reach its destination from source.

IPCONFIG Used to display Windows IP configuration information.

NSLOOKUP This utility enables users to interact with a DNS server and display resource records.

ROUTE Used to display and edit static routing tables.

NETSTAT is used to review all inbound / outbound TCP/IP connection..

WINS server resolves the NetBIOS names to IP addresses. The network need to be configured with WINS (or LMHOSTS file on each computer) for NetBIOS name resolution.

Never try to open the high voltage power supply in the field. It contain dangerous voltages and some times fatal. Replacing the power supply with a good one and sending the faulty one to the service center is appropriate.

46)NIC, Network Interface Card is the one that interfaces your PC to the LAN. NIC sits in your PC on one of the slot available on the motherboard.

Nickel Cadmium battery is not environmentally friendly and not as efficient as Nickel/Metalhydride or Lithium Ion. Nickel/Metal hydride, though environmentally friendly, not as efficient as Lithium Ion. Lithium Ion battery is environmentally friendly and very efficient.

Normally, desktop processors consume higher power compared to laptop processors. Laptop processors are optimized for lesser power consumption, so that the heap produced is also less. This is to take care of poor ventilation conditions in a laptop computer.

Normally, PATA (Parallel ATA) is used for connecting a hard disk in a notebook computer.

Normally, the printer supplier provides a driver that goes with the XP OS. It is always preferable to use the driver supplied by the device manufacturer along with the printer.

Note that if you want to make a multi boot system, Windows NT is not compatible with FAT32 file system. Windows 2000 supports FAT16/FAT32 and NTFS. Windows 95/ 98 does not support NTFS file system

NTFS 5 supports file encryption, where as NTFS 4 doesn't. You can upgrade NTFS 4 to NTFS 5 on Windows NT 4.0 computer by installing Service Pack 4 or later.

NTFS file system allows assigning of security permissions at file level and/or folder level.

47)NTLDR is responsible for switching Windows XP/2000 operating system from real mode to protected memory mode of operation.

Often manufacturers recommend using a pencil eraser to clean the connectors.Cotton swab dipped in IPA can also be used effectively.

Recommended cleaning procedures for various components are as below:

Computer Cabinet: Use mild detergent
Dust inside the computer: Use compressed air
Tape drive: Use tape drive cleaning catridge
Floppy drive: Use floppy drive cleaning kit
CD ROM drive: Use CD-ROM drive cleaning kit
Mouse: Use cotton swab with Isopropyl Alcohol.

Only Windows NT Server 4 and Windows NT Server 3.51 can be upgraded to Windows 2000 Server. Windows NT Workstation 4.0 or Windows 95/98 cann't upgraded to 2000 Server.

48)PAP uses 2-way handshaking. Passwords are sent in clear text across the link. Therefore, PAP is to be used only when it not possible to use CHAP.

CHAP uses 3-way handshaking. CHAP uses Challenge/ Response method which provides protection against the password capture while authenticating the user. One should use CHAP whenever it is possible.

Parallel cable is commonly used for printing. A standard Centronics Parallel Cable has a DB-25 connector at the computer end and Centronics 36 pin connector at the printer end.

On laptop computers, passive matrix displays are most commonly used and cheaper than Active matrix displays. Also, passive matrix displays consume less power. However, the advantages of active matrix display are: 1. They can handle faster screen image transition, and 2. The display is clearly viewable, even from slant angles.

49)PCMCIA cards are also known as PC cards. PCMCIA stands for Personal Computer Memory Card International Association.

PCI cards can be identified by the following attributes:

1. They have a single notch as shown in the exhibit.

2. Also, note that the finger contacts are very close.

The one shown in the exhibit is a Network Interface Card (NIC) that goes into a PCI slot on the motherboard. Note that PCI slots are smaller than the ISA slots. All ATX motherboards have PCI slots, and may or may not have ISA slots. AGP (Advanced Graphic Port) port is shorter than PCI slot and usually brown in color. A video card will have onboard video RAM sockets for adding video memory and also an output connect to connect to a video monitor.

Peer-to-peer model is best suited when you need to share files and folders among others in your office. If the number of networked computers becomes very large or if the security of data is very important, Client-Server model is recommended.

Philips screw driver uses "#" sign before the number, such as #1 to denote the size of the blade. Torx screw driver uses "T" sign before the number.

Possible reasons for slow running of a computer may include insufficient memory, viruses and Trojan horses, too many TSRs (Terminate and Stay Resident) running at the same time, etc. Ensure that your computer has sufficient memory, hard disk space, and anti-virus software installed (particularly if connected to the Internet).

50)Power On Self Test (POST) happens after the computer cold boots.

Pressing F8 during boot process in Windows 2000 desk top bring up the following options:

1. Safe Mode
2. Safe Mode with Networking
3. Safe Mode with Command prompt
4. Enable Boot Logging
5. Enable VGA Mode
6. Last Known Good Configuration
7. Debugging Mode
8. Boot Normally

Safe Mode loads only the drivers necessary to get the desk top up and running. The drivers loaded with Safe Mode include mouse, monitor, keyboard, hard drive, and standard video driver.

Safe Mode with Networking is same as Safe Mode with networking enabled.

Safe Mode with Command Prompt option loads the command prompt instead of Windows 2000 graphical interface.

Enable VGA Mode option loads a standard VGA driver. This option is good if you have any problem with newly installed video driver.

Last Known Good Configuration enables the desk top to load the configuration that was stored when it was booted successfully last time.

This option can't take care of any hardware related problems.

The Debugging Mode option runs the Kernel Debugger, if that utility is installed.

The Boot Normally is same as not pressing the F8 key. The Windows boots normally

51)Printer parallel ports come in the following varieties:

1. Unidirectional: Here, the data travels only from the computer to the peripheral(printer) device.
2. Bi-directional: Here, the data travels both from the computer to the peripheral device and vice-versa.
3. ECP (Extended Capability Port): ECP mode offers bi-directional data transfer, as well as DMA for data transfer.
4. EPP (Enhanced Parallel Port): In addition to bi-directional features, it offers an extended control code set.

RAM stands for Random Access Memory. There are basically tow types of RAM: 1. DRAM - Dynamic RAM, and SRAM - Static RAM. SRAM, being very expensive, normally used for Cache memory. DRAM, being cheaper, is normally used for main memory.

52)Riser card typically holds multiple IO cards.

RJ-11:These connectors are used to link modem / phone to the phone line. They have only two pins that get into the modem.

RJ-14: RJ-14 connectors are dual-line phone jacks that can accommodate up to two phone lines.

RJ-45: RJ-45 cable is widely used for attaching UTP cable in LANenvironment. These connectors have eight pins.

Running a command like "ping" or "ipconfig" will open the command screen. However, the command screen closes soon after the execution of the command. If you intend to observe the results of any such command, you need to open the DOS screen by going to Program Files | Accessories | Command Prompt.

53)When attending to a customer call, sensitive discussions overheard are confidential, and should be treated confidential.

Serial cable maximum length is 50 feet

Parallel cable maximum length is 10 feet

Longer cable lengths may lead to some errors & garbage characters

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