TFT Monitor Inside Look.

TFT Monitor Inside Look.

While there are many different manufacturers of TFT monitors, there are several main manufacturers of the panels themselves incorporated into these screens. 

How TFT Technology Works



My real time board-by-board lab explanation images.

System Administrator Interview Questions and Answers

Q. Describe how the DHCP lease is obtained. 

A. It’s a four-step process consisting of (a) IP request, (b) IP offer, © IP selection and (d) acknowledgement.

Q. I can’t seem to access the Internet, don’t have any access to the corporate network and on ipconfig my address is 169.254.*.*. What happened?

A. The 169.254.*.* netmask is assigned to Windows machines running 98/2000/XP if the DHCP server is not available. The name for the technology is APIPA (Automatic Private Internet Protocol Addressing).

Q. We've installed a new Windows-based DHCP server, however, the users do not seem to be getting DHCP leases off of it.

A. The server must be authorized first with the Active Directory.

Q. How can you force the client to give up the DHCP lease if you have access to the client PC? 

A. ipconfig /release

Q. What authentication options do Windows 2000 Servers have for remote clients?

A. PAP, SPAP, CHAP, MS-CHAP and EAP.

Q. What are the networking protocol options for the Windows clients if for some reason you do not want to use TCP/IP? 

 
A. NWLink (Novell), NetBEUI, AppleTalk (Apple).

Q. What is data link layer in the OSI reference model responsible for?

A. Data link layer is located above the physical layer, but below the network layer. Taking raw data bits and packaging them into frames. The network layer will be responsible for addressing the frames, while the physical layer is responsible for retrieving and sending raw data bits.

Q. What is binding order? 

A. The order by which the network protocols are used for client-server communications. The most frequently used protocols should be at the top.

Q. How do cryptography-based keys ensure the validity of data transferred across the network?  
 

A. Each IP packet is assigned a checksum, so if the checksums do not match on both receiving and transmitting ends, the data was modified or corrupted.

Q. Should we deploy IPSEC-based security or certificate-based security?

A. They are really two different technologies. IPSec secures the TCP/IP communication and protects the integrity of the packets. Certificate-based security ensures the validity of authenticated clients and servers.

Q. What is LMHOSTS file? 

A. It’s a file stored on a host machine that is used to resolve NetBIOS to specific IP addresses.

Q. What’s the difference between forward lookup and reverse lookup in DNS? 

A. Forward lookup is name-to-address, the reverse lookup is address-to-name.

Q. How can you recover a file encrypted using EFS? 

A. Use the domain recovery agent.

 

Networking Interview Questions

Computer Networks Interview Questions

What protocol is used by DNS name servers ?
DNS uses UDP for communication between servers. It is a better choice than TCP because of the improved speed a 

connectionless protocol offers. Of course, 

transmission reliability suffers with UDP.

What is the difference between interior and exterior neighbor gateways? 
Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside 

world.

What is RIP (Routing Information Protocol)
It is a simple protocol used to exchange information between the routers.


What is OSPF ?
It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an 

Internet's topology to make accurate routing decisions.

What is Kerberos ?
It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to 

prevent intruders from discovering passwords and 

gaining unauthorized access to files.

What is Mail Gateway? 

It is a system that performs a protocol translation between different electronic mail delivery protocols.

Why should you care about the OSI Reference Model

It provides a framework for discussing network operations and design.

What is the difference between routable and non- routable protocols

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are 

designed to work on small, local networks and cannot be 

used with a router.

What is the difference between TFTP and FTP application layer protocols ? (Asked in IBM Interview)

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.

The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offered by TCP and so is reliable and secure. It establishes

What is difference between ARP and RARP ?
The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used 

by a host or a router to find the physical address of 

another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its 

physical address.

What is ICMP ?
ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to 

send notification of datagram problems back to the 

sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both 

control and error messages.

What is Bandwidth ?
Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the 

bandwidth.

What is MAC address ?

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC 

address is usually stored in ROM on the network 

adapter card and is unique.

What is RAID
A method for providing fault tolerance by using multiple hard disk drives.


What is subnet ?
A generic term for section of a large networks usually separated by a bridge or router.


What is difference between baseband and broadband transmission
In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband 

transmission, signals are sent on multiple frequencies, allowing 

multiple signals to be sent simultaneously.

What are the possible ways of data exchange
(i) Simplex (ii) Half-duplex (iii) Full-duplex.

What is point-to-point protocol ?

A communications protocol used to connect computers to remote networking services including Internet service 

providers.

Understanding Windows Server & its Roles.

Understanding Windows Server & its Roles.

What is a Server ?

The term server refers to a machine that is providing a service for other machines, e.g. A computer which shares files on the network would be classed as a file server. For example, A Domain Controller is classed as a server because it is providing a service for the rest of the clients on the network. Windows 2003 can take several different server roles. 

File Server

A File Server stores files and folders that are used by other machines on the network. It can hold applications, text documents, or a user’s My Documents Folder.  For security, many shared folders are housed on file servers. A distributed file system is housed on more than one file server for the sake of fault-tolerance and ease of access.

A Windows XP Professional machine may act as a limited File Server.

A Windows Server 2003 Computer can also act as a file server for different operating systems, e.g. Apple Macintosh.

Print Server

A Print Server is a computer that has a printer attached to it and shares the printer for use on the network.

A Windows XP Professional Machine can be a reasonably capable Print Server.

Application Server

Besides being a Domain Controller, Windows Server 2003 can also be a host to many different services e.g. as a Database Server and a Terminal Server.

Some Common Microsoft Servers:

Microsoft Exchange allows you to setup an e-mail server and also allows you setup a messaging and collaboration system for your company’s network.

Microsoft SQL Server enables you to setup up powerful database servers for your company’s network.

Microsoft ISA Server allows you to setup an Internet Gateway/Proxy Server for your company’s network.

These applications require Windows Server 2003. Their integration with Active Directory allows for tighter security and easier administration.

A Database Server holds a database! This is not just a list of information. It is structured, and dynamic. It needs to be managed, updated, extended and secure, while at the same time being accessible to users.  A dedicated server is required for this.

Remote Administration enables an administrator to manage a server from almost any workstation on the network using Terminal Services. Terminal Services lets workstations use powerful applications housed at the server as if they were installed at that workstation.

Web Servers

A Web Server hosts and manages websites for the Internet or an intranet. Because of the need to manage heavy and burst-mode traffic while maintaining security, a dedicated server is recommended.

Windows 2003 can function as a web server using the Internet Information Services (IIS) service

Windows XP Professional ships with a limited version of IIS which allows a workstation to host a single website.

Networking - What is ARP Cache

ARP is a component which helps to make up the networking functionality of the computer. The ARP allows for computers to be connected to each other in a network using a MAC Address, while still being connected to the wider internet using an internet protocol (IP) address issued by the internet service provider (ISP).

The ARP networking component is best understood as being a repository of information regarding the connection to other computers and networks by using MAC Addresses and IP addresses to engage in networking functionality. Once the computer has communicated with another computer, the response which identifies the computer to be connected to is stored in the ARP Cache. The ARP cache then stores the resolved IP address from the website to be connected to. Eventually, credentials change for successful connection to other computers; as a result, emptying the ARP Cache and rebuilding the file may be a solution to internet and network connection issues.

Rebuilding the ARP cache really refers to clearing or deleting the contents of the cache. Clearing the ARP cache is accomplished by using the Microsoft Windows Command Prompt.
To access the Command Prompt, navigate using the “Start” menu in the taskbar to “Programs”, “Accessories” then “Command Prompt”. At the prompt, type the following without quotations marks: “netsh interface ip delete arpcache” then press the “ENTER” key on the keyboard. The command will delete the entire contents of the ARP cache and rebuild connection and other details needed. With the ARP cache now cleared, all wanted connections can now be made.

For some, however, clearing the ARP cache may have been unsuccessful due to an error in the programming of the Microsoft Windows operating system. In such cases, the user is expected to manually disable the service “Routing and Remote Services”. Navigate to the “Control Panel” from the “Start” menu and open the “Administrative Tools” feature in the Control Panel.
In Administrative Tools, click on “Computer Management” then select “Services and Applications”. Select “Services” and double click the entry “Routing and Remote Services”.
The “Startup Type” should be changed from “Automatic” or “Manual” to “Disabled”. With the service disabled, it will not start after shutdown or reboot. After disabling the service, verify it has stopped by clicking the “Stop” button under the “Service Status” section.

The two aforementioned procedures should be able to allow the ARP cache to be cleared, rebuilt and free from any Microsoft Windows service interruption or intervention allowing for free connectivity between computers, networks and other network peripherals.

Try to maintain the ARP cache regularly to keep the cache free of any future conflicts.