Router vs Switch

	Router	Switch
Layer	Network Layer (Layer 3 devices)	Data Link Layer. Network switches operate at Layer 2 of the OSI model.
Ports	2/4/8	Switch is multi port Bridge. 24/48 ports
Device Type	Networking device	Active Device (With Software) & Networking device
Data Transmission form	Packet	Frame (L2 Switch) Frame & Packet (L3 switch)
Transmission Type	At Initial Level Broadcast then Uni-cast & Multicast	First broadcast; then unicast & multicast as needed.
Function	Directs data in a network. Passes data between home computers, and between computers and the modem.	Allow to connect multiple device and port can be manage, Vlan can create security also can apply
Table	Store IP address in Routing table and maintain address at its own.	A network switch stores MAC addresses in a lookup table.
Transmission Mode	Full duplex	Full duplex
Used in (LAN, MAN, WAN)	LAN, WAN	LAN
Broadcast Domain	In Router, every port has its own Broadcast domain.	Switch has one broadcast domain [unless VLAN implemented]
Definition	A router is a networking device that connects a local network to other local networks. At the Distribution Layer of the network, routers direct traffic and perform other functions critical to efficient network operation.	A network switch is a computer networking device that is used to connect many devices together on a computer network. A switch is considered more advanced than a hub because a switch will on send msg to device that needs or request it
Device Category	Intelligent Device	Intelligent Device
Bandwidth sharing	Bandwidth sharing is Dynamic (Enables either static or dynamic bandwidth sharing for modular cable interfaces. The default percent-value is 0. The percent-value range is 1-96.)	There no sharing port can be 10, 100, 1000 and 10000 Mbps individual
Speed	1-10 Mbps(Wireless) 100 Mbps (Wired)	10/100Mbps, 1Gbps
Routing Decision	Take faster Routing Decision	Take more time for complicated routing Decision
NAT (Network Address Translation)	Can Perform NAT	Switches can Not perform NAT
Faster	In a different network environment (MAN/ WAN) Router is faster than L3 Switch.	In a LAN environment L3 switch is faster than Router (built in switchning hardware)
Features	Firewall VPN Dynamic hadling of Bandwidth	Priority rt range On/Off setting of port VLAN Port mirroring
Latest Models	Linksys WRT54GL Juniper MX & EX series Cisco 3900,2900,1900	Alcatel's OmniSwitch 9000; Cisco Catalyst switch 4500 and 6500(10 Gbps),
Used for	Connecting two or more networks	Connecting two or more nodes in the same network or different network
Address used for data tramsmission	Uses IP address	Uses MAC address

Source: http://www.diffen.com/difference/Router_vs_Switch

Reset forgotten/lost main user password in Linux

You can reset your password following the next steps:

1. Reboot your computer / Turn your computer on.
2. Hold down the Shift key at the start of the boot process to enable the GNU GRUB boot menu (if it does not show)
3. Press ESC at the GNU GRUB prompt.
4. Press e for edit.
5. Use the Arrow keys to highlight the line that begins with kernel and press the e key.
6. Go to the very end of the line and add rw init=/bin/bash
7. Press Enter and then press b to boot your system.
8. Your system will boot up to a passwordless root shell.
9. Type in passwd yourusername
10. Set your new password.
11. Restart your system.

Note:- Above steps only work with Linux installed with 'grub'

Source:http://community.linuxmint.com/tutorial/view/339

404 error while accessing weblogic application

If you are facing 404 error while accessing Weblogic application even if the application shown as in 'Active' status in deployment page.

Solution: Redeploy the application.

Linux disk sharing.

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Disk sharing between two Linux systems:-

Machine1:-

1. Find the folder/directory you want to share (eg: /opt/directory)
2. Add this directory in /etc/exports (need root permission) as mentioned
   • /opt/directory *(rw)
   • Format: directory machine1(option11,option12)
     • directory - the directory that you want to share. It may be an entire volume though it need not be. If you share a directory, then all directories under it within the same file system will be shared as well.
     • machine1 - client machines that will have access to the directory. The machines may be listed by their DNS address or their IP address (e.g., machine.company.com or 192.168.0.8). Using IP addresses is more reliable and more secure.
     • optionxx
       the option listing for each machine will describe what kind of access that machine will have. Important options are:
       • ro: The directory is shared read only; the client machine will not be able to write to it. This is the default.
       • rw: The client machine will have read and write access to the directory.
       • no_root_squash: By default, any file request made by user root on the client machine is treated as if it is made by user nobody on the server. (Excatly which UID the request is mapped to depends on the UID of user "nobody" on the server, not the client.) If no_root_squash is selected, then root on the client machine will have the same level of access to the files on the system as root on the server. This can have serious security implications, although it may be necessary if you want to perform any administrative work on the client machine that involves the exported directories. You should not specify this option without a good reason.
       • no_subtree_check: If only part of a volume is exported, a routine called subtree checking verifies that a file that is requested from the client is in the appropriate part of the volume. If the entire volume is exported, disabling this check will speed up transfers.
       • sync: By default, all but the most recent version (version 1.11) of the exportfs command will use async behavior, telling a client machine that a file write is complete - that is, has been written to stable storage - when NFS has finished handing the write over to the filesysytem. This behavior may cause data corruption if the server reboots, and the sync option prevents this.
3. Run /etc/init.d/nfs restart

Machine 2:-

1. mkdir /opt/directory (any other directory also fine.)
2. mount machine1.hostname:/opt/directory /opt/directory or
3. Add “machine1.hostname:/opt/directory /opt/directory nfs auto 0 0” to your /etc/fstab file.

How to install Open Office in Oracle Enterprise Linux?

1. Use below yum command:
sudo yum -y install openoffice.org*

2. Download rpm file from http://sourceforge.net/projects/openofficeorg.mirror/files/4.0.1/binaries/en-US/Apache_OpenOffice_4.0.1_Linux_x86-64_install-rpm_en-US.tar.gz/download
and follow the instructions mentioned @ http://www.openoffice.org/download/common/instructions.html#linux-rpm
Another download link http://www.openoffice.org/download/other.html with language specific installers.

How to override:- Some settings are managed by your administrator

Configure Automatic Updates by using local Group Policy

1.       Click Start, and then click Run.
2.       Type gpedit.msc, and then click OK.
3.       Expand Computer Configuration.
4.       Right-click Administrative Templates, and then click Add/Remove Templates.
5.       Click Add, click Wuau.adm in the Windows\Inf folder, and then click Open.
6.       Click Close.
7.       Under Computer Configuration, expand Administrative Templates, expand Windows Components, and then expand Windows Update.

The Configure Automatic Updates policy appears. This policy specifies whether the computer receives security updates and other important downloads through the Windows Automatic Updates feature. By using the settings for this policy, you can specify whether automatic updates are enabled on the computer. If the service is enabled, you must select one of the three configuration options.
8.       To view the policy settings, double-click the Configure Automatic Updates policy.
9.       To turn on Automatic Updates, click Enabled in the list of options that appear at the top of the Setting tab.
If you click Enabled, you must select one of the configuration options that is described in step 10.
10.    Select one of the following options:

2 - Notify for download and notify for install
When updates are available, an icon appears in the notification area and you receive a message that states that the updates are ready to be downloaded. Click the icon or the message to view and select the updates that you want to download. Windows downloads the updates in the background. When the download is complete, an icon appears in the notification area and you receive a message that states that the updates are ready to be installed. You can click the icon or the message to select the updates that you want to install.


3 - Auto download and notify for install
Note This is the default setting.
When updates are available, Windows downloads the updates in the background. The user is not notified or interrupted during this process. When the download is complete, an icon appears in the notification area and you receive a message that states that the updates are ready to be installed. You can click the icon or the message to view and select the updates that you want to install.

4 - Auto download and schedule the install
To specify the schedule, select the appropriate options in the Group Policy Settings dialog box. If you do not specify a schedule, updates are installed daily at 3:00 A.M by default. Windows restarts the computer automatically if it is necessary. If someone is using the computer when Windows is ready to restart it, a notification appears that states that Windows needs to restart the computer. The user can choose to restart the computer later.

If you select 4 - Auto download and schedule the install, you can set a recurring schedule. If you do not set a schedule, all updates are downloaded and installed every day at 3:00 A.M.

Other Options
Additionally, you can select the Disabled option or the Not Configured option. If you select Disabled, an administrator must download and install any available updates manually from the Microsoft Windows Update website.

If you select Not Configured, the status of Automatic Updates is not specified at the Group Policy level. The status is either "enabled" or "not enabled." However, an administrator can still configure Automatic Updates by using Control Panel. Control Panel includes the same settings that are available in Group Policy.

Note An updated Administrative Template (.adm file) is now available for use with the Automatic Updates feature in Windows Server 2003 and the Software Update Services (SUS) Service Pack 1 (SP1) client. This updated policy file adds two new policies:

• Reschedule Automatic Updates scheduled installations

This policy specifies the time period that Automatic Updates must wait after the computer starts, before it continues with a scheduled installation that was missed previously.

• No auto-restart for scheduled Automatic Updates installations

This policy specifies that Automatic Updates will complete a scheduled installation when any user who is logged on restarts the computer. If this policy is not used, the computer restarts automatically.

Source : http://support.microsoft.com/kb/328010