Repairing the ntldr missing problem - Windows XP/2000/2003

Here is how a Windows XP machine can recover from the ntldr missing problem.

Figure 1 shows the typical error message of the problem:

Fig: 1

Step1:

Boot the machine using Windows XP bootable CD. After sometime the setup shows options like Figure 2:

Fig: 2

Step2:

Here, press R to enter the Recovery Console. When you entered, the recovery console will display the windows directories in your system and asks for your choice. See Figure 3:

Fig: 3

Here, enter the option number (Eg: 1) of your windows directory. Now, you will be asked to enter the administrator password of your OS. Enter it to get access to the repair console. (Ref: Figure 4)

Fig: 4

Step3:

Now you have access to some windows commands here. We just need to restore the missing files to the installation drive. For that, enter the following commands in order.

1. copy D:\i386\ntldr C:\
   (Here D is the CD drive )
2. copy D:\i386\ntdetect.com C:\
3. attrib + rhs C:\ntldr
4. attrib +rhs C:\ntdetect.com

Fig: 5

Type exit command to restart your machine.
That is all, Enjoy..
For a better reference, watch the demonstration video here:

NB: This method works only if your system is not booting because of losing ntldr or ntdetect or both files..

Mozilla Firefox Mouse Shortcuts.

   Ctrl + Scroll Up                              :           Zoom In

   Ctrl + Scroll Down                         :           Zoom Out

   Double-Click on Tab Bar              :          New Tab

   Middle-Click                                   :          Scroll Lock

   Middle-Click on Tab                      :          Close Tab

   Shift + Scroll Up                             :          Forward

   Shift + Scroll Down                        :          Back

   Shift + Left-Click                            :         Open in New Window

   Shift + Reload Button                    :         Reload but Overrides Cache

   Ctrl + Drag                                      :         Copy Tab or Bookmark

   Alt + Left-Click                               :         Save Page As

   Alt + Scroll                                      :         Scroll line by line

Mozilla Firefox Keyboard Shortcuts

Ctrl + N                                        :     Open New browser window.
Ctrl + P                                         :     Print current page / frame.
Ctrl + T                                        :     Opens a new Tab.
Ctrl + F4 or Ctrl + W                  :     Closes the currently selected tab.
Ctrl + Shift + W or Alt + F4        :     Close the current window.
Ctrl + Shift + T                            :     Undo the close of a window.
Ctrl + Tab or Ctrl + Page Down  :     Go to next Tab(Left to Right).
Ctrl + (1 to 8)                               :     Select Tab from 1 to 8.
Ctrl+9                                           :     Select Last Tab.

Ctrl + Shift + Del                         :    Open the Clear Data window to quickly clear private data.
Ctrl + D                                        :     Add  Bookmark for the page currently opened.
Ctrl + I                                         :     Display available bookmarks.
Ctrl + J                                         :     Display the download window.
Spacebar                                      :     Moves down a page at a time.
Shift + Spacebar                          :     Moves up a page at a time.
Alt + Down arrow                        :     Display all previous text entered in a text box and/or available options on Drop down menu.
Alt + Left Arrow                          :     Back a page.
Backspace                                    :    Back a page.
Alt + Right Arrow                        :     Forward a page.
F5                                                  :    Refresh current page, frame, or tab.
F11                                                :    Full screen mode.
Esc                                                :    Stop page or download from loading.
Ctrl + (- or +)                                :    Increase or decrease the font size, pressing '-' will decrease and '+' will increase.
Ctrl + Enter                                  :    Quickly complete an address. For example, type google in the address bar and press CTRL + ENTER to get http://www.google.com.
Shift + Enter                                 :    Complete a .net instead of a .com address.
Ctrl + Shift + Enter                      :    Complete a .org address.

Classifications of Networks-Part 4

Networking Models

Peer-to-Peer(Workgroup) Model

Peer-to-Peer Model

Peer-to-Peer or simply P2P is a networking model in which each computer in the network has the same priorities or rights when communications are done. That is there is no central nodes or namely servers to manage and control other nodes in the network.  In some cases, peer-to-peer communications is implemented by giving each communication node both server and client capabilities. Because of  these reasons, the P2P is a less secure networking model.

                                            The Peer-to-peer model is also known as Workgroup Model, because the computers working in this model are said to be lied in a Workgoup (A group of computers).

Advantages

1. Easy to setup the network.
2. No dedicated nodes needed.
3. Less expensive.
4. Suitable for small networks with ten to twenty nodes.
5. Local users can control their shared resources.

Disadvantages

1. Less Secure.
2. Less Reliable.
3. Difficult to Administrate.

Client-Server(Domain) Model

Client-Server Model

This is a much secure networking model compared to P2P. In a server-client network, there must have a special computer called server and the others will be clients. A Server is typically a computer which provides service, but here we are using the term server to denote a specific node which has the ability to control and manage other nodes which we calls as clients. Clients are nodes which receives services from a server.

                                 In most conditions, servers only gives some software resources(or a Database) for the clients to use their computer under the control of the server and do their work that are allowed by the server. That is most servers are not intended to give their processing capability or storage capacity to clients. All these resources should exist in the client computer itself.

                The servers must have specific server operating systems installed on it.Some popular server OS's are Windows 2000 Server, Windows 2003 Server, Windows 2008 Server, Redhat Enterprise Linux, Ubundu Server. Clients only need any desktop level OS such as Windows XP, Windows Vista, Windows 7 or Ubundu Desktop.

Advantages

1. Having a dedicated high end machine as server will increase the network performance.
2. Highest level of security(Centralized control of data).
3. Highly expandable.
4. Easy administration compared to P2P.
5. More reliable than P2P.

Disadvantages

1. Server should be dedicated with high configuration hardwares and specific networking softwares(including OS).This is expensive.
2. Server should always be available.
3. Need a full time administrator to maintain the network.
4. Maintenance also is expensive.

Classifications of Networks-Part 3

Network Topologies

                                 A network Topology means, the physical arrangement of computers,devices and cables in a network.

Bus Topology  

In Bus topology network devices uses a common backbone in a linear shape to communicate in the network. All the devices should be attached with this single shared cable with an interface connector. The device, which wants to communicate send a broadcast message to all the devices attached with the shared cable but only the intended recipient will accepts and process that message.

Bus Topology

Advantages

1. Easy to setup a network.
2. Easy to expand.
3. Suited topology for small networks.
4. Less expensive compared to other topologies.                                  

Disadvantages

1.  Slower data transfer rate.
2. Cable length and number of nodes that can connected are limited.
3. If the backbone cable fails, the whole network will fails.
4. Heavy network traffic when number of nodes are increased.

Ring Topology 

Ring Topology

In this topology computers are arranged in a ring manner. That is every computer or devices in this network should have two neighbors for communication. All the communications will be in the same direction, either clockwise or anti-clockwise. 

                              FDDI (Fiber Distributed Data Interface) or Token Ring Technology can be used to implement Ring Technology. Ring topologies can be found in office, school or small buildings.

Advantages

1. Chances of collision is very low.
2. Better performance than a Bus topology.

Disadvantages

1. Failure of one computer or port can cause the whole network to fail.
2. Adding, moving or removing devices can affect the network.
3. Slower than Star topology under normal load.
4. It is difficult to troubleshoot a ring network.
5. Network cards are expensive compared to Ethernet cards and hubs.

Mesh Topology

Mesh Topology

In a mesh topology, each device in the network are interconnected to one another to provide an almost always up network connectivity. That is each device remains in the network even if one or two of the connections go down. As this topology is difficult and expensive to configure, it is not commonly used in most computer networks.

Advantages

1. Data can be transmitted from one node to many nodes and vice versa simultaneously.
2. Less traffic problems.

Disadvantages

1. Configuration of network is complex and expensive.
2. Difficult to manage the network.

Star Topology

Star topology is the most commonly used topology in LAN. A star topology links the computers by individual cables to a centralized connectivity device, usually a hub or switch. The commonly used cable is the Unshielded Twisted Pair (UTP) or Shielded Twisted Pair (STP).

Star Topology

Advantages

1. Easy to setup and expand the network. 
2. Adding, moving or removing devices will not affected to the entire network.
3. Better performance than other topologies.                  
4. Failure of one device or link will not affect the whole network.
5. Centralization of network will help to analyze the traffic.
6. Easy to troubleshoot.

Disadvantages

1. Dependency to the central device(Hub or Switch) is the main drawback. If it fails, the entire network goes down.
2. Expansion and performance of the network is depended on the capacity of the central device.
3. Need of the expansion devices(Hubs, Switches or Routers) will make the network expensive.

Classifications of Networks-Part 2

According to Geographical conditions

• LAN (Local Area Network) : A Local Area Network covers only a localized or small physical area such as Home, Office, building or a small groups of building such as a school, or an airport.A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LAN's, and to the Internet or other WAN.Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, Network adapters, and Hubs/Switches. Wireless LAN and other more advanced LAN hardware options also exist.

Local Area Network

• MAN (Metropolitan Area Network) : A MAN is simply a network which interconnects a number of  Local Area Networks (LAN's) using a high-capacity backbone technology, such as fiber-optical links and spans a city or a large campus. A MAN often provides

Classifications of Networks - PART 1

                                    Networks can be classified into many according to its different characteristics. We can mainly divide networking into two categories,

• Wired Networking :  Wired networks are established by connecting computers or devices using some type of networking cables such as UTP (Unshielded Twisted Pair). Wired networks provide users with plenty of security and the ability to move lots of data very quickly. Wired networks are typically faster and reliable than wireless networks, and they can be very affordable. A notable drawback of wired network is that the cost of cables will make it expensive when more computers are added to the network. It can also make problems with the wires, because it can greatly limit the mobility of devices.

Wired Network

• Wireless Networking : Wireless networks are those which uses radio waves instead of cables to for computers to communicate. It is easiest and least expensive way to connect the computers, but slower and less secure compared to wired. They are more flexible than the wired networks because of the absence of physical wires.

Wireless Network

Mozilla Firefox Master Password

To help secure your password information from anyone else using Firefox or from anyone that could steal your computer follow the below steps to setup a Master Password.

1. Open Firefox and click Tools and then Options.
2. From the Options window, select the Security tab.
3. Check the Use a master password option.
4. Enter your master password and click OK. From now, no one without having the master password can neither View or Delete the saved passwords nor can Add new passwords to the list.

To view or delete Saved Passwords click the Saved Passwords button on the Security tab and then click Show Passwords option. Enter your master password and you can see the passwords.

Lock your personal folder without using any software.

First, locate the folder which you want to lock. Suppose, DATA is your private folder and it is stored in D:\ drive.

In the same drive ( ie, D:\) you need to create a batch file. For this, Do the following steps:

1. Open Notepad, Start>Programs>Accessories>Notepad
2. Type, ren data data.{21EC2020-3AEA-1069-A2DD-08002B30309D}
3.  Now, take File menu and click Save  (The Save As window appears)
4. Here, Select D drive in the Save in option and give File name as "Lock.bat" (with quotes)
5. Click Save and close it.

Now open D drive where your folder DATA is, there should be a file named Lock, Double click it. Now the folder DATA's icon will be changed to Control Panel icon.
Try to open the folder DATA, it will open the Control Panel instead of your folder. It is Locked!!


To Unlock

To create another batch file.(Do this only when necessary and delete after use.)

1. Open Notepad, Start>Programs>Accessories>Notepad
2. Type, ren data.{21EC2020-3AEA-1069-A2DD-08002B30309D} data
3.  Now, take File menu and click Save  (The Save As window appears)
   
4. Here, Select D drive on the Save in option and give File name as "Unlock.bat" (with quotes)
5. Click Save and close it.

Now, Open D drive and Double click on unlock.bat and you will get back your original folder.

NB: Try at your own Risk.