How Does DHCP Work?

DHCP works by leasing IP addresses and IP information to network clients for a period of time. For the lease to happen, the following negotiation process occurs:

Lease Request
1. During the boot process, a client computer that is configured as a DHCP client sends out a broadcast packet called DHCPDISCOVER. This Discover packet contains the client's computer name and Media Access Control (MAC) address so the DHCP servers can respond to it. Basically, the Discover packet says, "I'm looking for a DHCP server who can lease an IP address."

Lease Offer
2. DHCP servers on the network respond to the broadcast with a DHCPOFFER. In essence, the DHCPOFFER says, "I am a DHCP server and I have a lease for you." If several DHCP servers respond to the request, the client accepts the first offer that it receives.

Lease Selection
3. The client responds via a broadcast message called a DHCPREQUEST. This message basically says, "I accept your lease offer and would like an IP address." If other DHCP servers made offers, they also see their lease offers were not accepted by the broadcast message, so they rescind their offers. (They must not like getting snubbed by a client computer.)

Lease knowlegment
4. The DHCP server whose offer was accepted responds with a DHCPACK message, which acknowledges the lease acceptance and contains the client's IP address lease as well as other IP addressing information that you configure the server to provide. The client is now a TCP/IP client and can participate on the network.

Node.js Links

1.  http://nodeguide.com/
2. http://nodetuts.com/
3. http://howtonode.org/
4. http://www.nodebeginner.org/#about
5. http://www.lynda.com/Nodejs-tutorials/Nodejs-First-Look/101554-2.html
6. http://nodejs.org/
7. http://debuggable.com/posts/understanding-node-js:4bd98440-45e4-4a9a-8ef7-0f7ecbdd56cb

Git Commands

The most commonly used git commands are:
   add        Add file contents to the index
   bisect     Find by binary search the change that introduced a bug
   branch     List, create, or delete branches
   checkout   Checkout a branch or paths to the working tree
   clone      Clone a repository into a new directory
   commit     Record changes to the repository
   diff       Show changes between commits, commit and working tree, etc
   fetch      Download objects and refs from another repository
   grep       Print lines matching a pattern
   init       Create an empty git repository or reinitialize an existing one
   log        Show commit logs
   merge      Join two or more development histories together
   mv         Move or rename a file, a directory, or a symlink
   pull       Fetch from and merge with another repository or a local branch
   push       Update remote refs along with associated objects
   rebase     Forward-port local commits to the updated upstream head
   reset      Reset current HEAD to the specified state
   rm         Remove files from the working tree and from the index
   show       Show various types of objects
   status     Show the working tree status
   tag        Create, list, delete or verify a tag object signed with GPG

See 'git help ' for more information on a specific command.

Power Options (for Lid Closed) Disabled

It's the Samsung Fast Start program that causes the disabled options.

To fix it:

Go to Start/All Programs/Samsung/Fast Start, which will open and you will see the default setting is 'On'. Select 'Off'. 

Go back to the power option controls and the option to 'Do Nothing' for Lid Close Action will be there.

Pretty quick fix.

How to recover files from RAW filesystem.

"RAW filesystem" issue typically occurs when the filesystem type information is missing or inconsistent between several system tables. Such an issue is often associated with external drives unplugged without "Safely removing" them first. The tables often get damaged during unsafe removal.

The "RAW filesystem" is generally recovered quite well. The typical scenario is to recover data from a device with a RAW filesystem, then format the device and copy the recovered data back to the device.

The most typical symptom of RAW filesystem is that Windows prompts "You need to format the disk before you can use it"

Important: do not format the disk if you need to recover data from it.

RAW filesystem recovery using ReclaiMe File Recovery

1. Make sure you have enough free space on a known-good drive or on a network to hold all the recovered data.
2. Download, install, and run ReclaiMe File Recovery software.(This requires a license,so please search for the same software with crack)
3. Identify the drive with a RAW filesystem in the device list. Most likely, it will have RAW listed as a filesystem type.
   
   (need help identifying your drive?).
4. Double click that drive to start recovery.
5. The files are displayed as soon as they are discovered.
6. Select the file(s) or folder(s) you want to recover, and click Save button on the toolbar. Alternatively, click Save and select Save All from the menu.
7. After data is copied, verify that the files were recovered correctly by actually opening and reviewing them.
8. Once the successful recovery is confirmed, reformat the drive and put it back to use.

Import/Export of Internet Explorer Security settings

These settings are only stored in the registry, most likely in the following key:
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]

1. To gain access to the registry, click Start|Run, type regedit, and click Enter.
2. Choose File|Export and choose "All" in the Export Range section, saving the file as "Backup.reg".
3. Navigate to the above mentioned key.
4. You'll want to export (Right-click->Export) the following keys from here:
   • ZoneMap
   • Zones
5. You could probably save them as "ZoneMap.reg" and "Zones.reg", respectively.
6. Upon exporting these keys, copy the REG files to the other computer.
7. Once completed, you'll want to open the registry and create a backup as on the first machine (Steps 1 & 2).
8. Close the Registry Editor.
9. Double-click "ZoneMap.reg" and "Zones.reg", one-at-a-time, clicking Yes in the prompt that appears.
10. If you mess anything up, just double-click the "Backup.reg" file you created earlier and click Yes in the prompt.

You can use "ZoneMap.reg" and "Zones.reg" on as many machines as you need to, just remember to create new copies whenever you need to change anything. 

The following link is to a Microsoft KB article with more information:
http://support.microsoft.com/kb/182569

TAR Command

The tar (i.e., tape archive) command is used to convert a group of files into an archive.

An archive is a single file that contains any number of individual files plus information to allow them to be restored to their original form by one or moreextraction programs. Archives are convenient for storing files as well as for for transmitting data and distributing programs. Moreover, they are very easy to work with, often much more so than dealing with large numbers of individual files.

Although tar was originally designed for backups on magnetic tape, it can now be used to create archive files anywhere on a filesystem. Archives that have been created with tar are commonly referred to as tarballs.

 1. Creating an archive using tar command

Creating an uncompressed tar archive using option cvf

This is the basic command to create a tar archive.

$ tar cvf archive_name.tar dirname/

In the above command:

c – create a new archive

v – verbosely list files which are processed.

f – following is the archive file name

Creating a tar gzipped archive using option cvzf

2.The above tar cvf option, does not provide any compression. To use a gzip compression on the tar archive, use the z option as shown below.

tar cvzf archive_name.tar.gz dirname/

z – filter the archive through gzip

Note: .tgz is same as .tar.gz

3.Files can be added to an existing archive using the -r option

tar -rf file.tar file7

4. The --delete option allows specified files to be completely removed from a tar file

tar -f file.tar --delete file1 file2

5. The -t option tells tar to list the contents of an uncompressed archive without performing an extraction. Thus, the following would list the contents of file.tar

tar -tf file.ta

6.In order to unpack a tar file, the -x (for extract) and -f options are required

tar -xvf file.tar

For more info visit:

http://www.thegeekstuff.com/2010/04/unix-tar-command-examples/#more-4101

http://www.linfo.org/tar.html