អ្វីជា GPU?

GPU មានពាក្យពេញជា Graphics Processing Unit ឫអាចហៅម្យ៉ាងទៀតថា Visual Processing Unit(VPU)។ វាគឺជា Circuit មួយដែលត្រូវបានរចនាយ៉ាងពិសេសសម្រាប់ចែកចាយ ឫផ្លាស់ប្តូរសមត្ថភាពលើការបង្ហាញគុណភាពរូបភាពនៅក្នុងអេក្រង់។ GPU ត្រូវបានប្រើប្រាស់នៅក្នុងទូរស័ព្ទដៃ កុំព្យូទ័រ ឧបករណ៍លេងហ្គេម និង Device ផ្សេងៗទៀត។

Forgot the root password for my RedHat Enterprise Linux 5 Server

ខ្ញុំបានដំឡើង RedHat Enterprise Linux 5 នៅក្នុង VMware Workstation មួយសន្ទុះក្រោយមកបានភ្លេចលេខសំងាត់របស់ root។ ខ្ញុំអាច Login ជា user ធម្មតាបាន ប៉ុន្តែវាគ្មានសិទ្ធិក្នុងការកែប្រែនោះទេ។ ខាងក្រោមនេះខ្ញុំនិងធ្វើការបង្ហាញនូវការផ្លាស់ប្តូរ password របស់ root:

To enter single user mode, reboot the server. When you see the RedHat Enterprise Linux 5 splash screen, press any key to enter the boot menu.

Press 'e' key to edit the commands before booting

How to Configure Static Route?

To configure Static Routes, first enter global configuration mode to run the following commands.

Configure the Static Routes on R1

R1>enable

R1#configure terminal

R1(config)#ip route 192.168.2.0 255.255.255.0 192.168.1.2

R1(config)#ip route 192.168.3.0 255.255.255.0 192.168.1.2

R1(config)#exit

R1#

Introduction to Static Routes and Default Routes

What is a Static Route?

A Static Route is a route that is created manually by a network administrator. Static routes are typically used in smaller networks. In static routing, the routing table entries are populated manually by a network administrator.

The opposite of a static route is a dynamic route. In dynamic routing, the routing table entries are populated with the help of routing protocols.

The major advantages of static routing are reduced routing protocol router overhead and reduced routing protocol network traffic. The major disadvantages of static routing are network changes require manual reconfiguration in routers and network outages cannot be automatically routed around. Also it is difficult to configure static routing in a complex network.

What is a Default Route?

A Default Route (also known as the gateway of last resort) is a special type of static route. Where a static route specifies a path a router should use to reach a specific destination, a default route specifies a path the router should use if it doesn't know how to reach the destination.

Default Route is the network route used by a router when there is no other known route exists for a given IP datagram's destination address. All the IP datagrams with unknown destination address are sent to the default route.

How to configure Passwords to secure Cisco Router

How to password protect Console Port

To configure the console password, follow these steps

Router>enable

Router#configure terminal

Router(config)#line console 0

Router(config-line)#password cisco

Router(config-line)#login

Router(config-line)#end

Router#

How to password protect Auxilary (AUX Port) Port

To configure the auxilary password, follow these steps

Router>enable

Router#configure terminal

Router(config)#line aux 0

Router(config-line)#password cisco

Router(config-line)#login

Router(config-line)#end

Router#

Cisco IOS Command Line Modes

Cisco IOS has a Command Line Interface (CLI) and it has three command line modes. Each mode has access to different set of IOS commands.

User mode

User mode is the first mode a user has access to after logging into the router. The user mode can be identified by the > prompt following the router name. This mode allows the user to execute only the basic commands, such as those that show the system's status. The router cannot be configured or restarted from this mode.

The user mode can be identified as shown below
Router>

How to configure Solarwinds Trivial File Transfer Protocol (TFTP) Server to backup IOS and configuration files

Solarwinds Trivial File Transfer Protocol (TFTP) Server is a free TFTP Server product from Solarwinds. After the installation of Solarwinds Trivial File Transfer Protocol (TFTP) Server in a computer, you need to configure it to backup IOS and configuration files of Cisco Routers and Switches.

Follow these steps to configure Solarwinds Trivial File Transfer Protocol (TFTP) Server
1, Make sure that the computer on which Solarwinds Trivial File Transfer Protocol (TFTP) Server is on the same network and the TCP/IP settings of the computer is on the same network where the router interface is connected. In our environment, the IP Address of the fa0/0 interface 192.168.1.1/24.

If you want to configure the IP address for the routers fa0/0 interface, follow these steps.

hour4khmer.R1>enable

hour4khmer.R1#configure terminal

hour4khmer.R1(config)#interface fa0/0

hour4khmer.R1(config-if)#ip address 192.168.1.1 255.255.255.0

hour4khmer.R1(config-if)#no shutdown

hour4khmer.R1(config-if)#exit

hour4khmer.R1(config)#exit

hour4khmer.R1#

To configure TCP/IP settings of the computer similar as below. Here the IP address of the computer where Solarwinds Trivial File Transfer (TFTP) Server installed is 192.168.1.10/24.

Test the connectivity by pinging to the router.
 

Cisco's Three-tier Hierarchical Network Model

Cisco uses a three-tier hierarchical network model, that consists of three layers: the Core layer, the Distribution layer, and the Access layer.

Core Layer

Core Layer consists of biggest, fastest, and most expensive routers with the highest model numbers and Core Layer is considered as the bone of networks. Core Layer routers used to merge geographically separated networks. The Core Layer routers move information on the network as fast as possible.

Distribution Layer

Distribution Layer includes LAN-based routers and layer 3 switches. Distribution Layer ensures that packets are properly routed between subnets and VLANs in your enterprise.

Access Layer

Access Layer includes hubs, switches and routers to segment LAN. Access Layer ensures that packets are delivered to end user computers.

Different Types of Router Memory

ROM (Read Only Memory)

ROM is read-only memory available on a router's processor board. The initial bootstrap software that runs on a Cisco router is usually stored in ROM. ROM also maintains instructions for power-on self test (POST) diagnostics. For ROM Software upgrades, the pluggable chips on the motherboard should be replaced.

Flash Memory

Flash Memory is an Electronically Erasable and Re-Programmable memory chip. The Flash memory contains the full Operating System Image (IOS, Internetwork Operating System). This allows you to upgrade the OS without removing chips. Flash memory retains content when router is powered down or restarted.

RAM (Random Access Memory)

RAM is very fast memory that loses its information when the system is restarted. On a router RAM is used to hold IOS system tables and buffers. RAM memory is basically used for all system operational storage requirements. RAM Stores routing tables, Keeps ARP cache, Performs packet buffering (shared RAM) and RAM Provides temporary memory for the router configuration file of the router while the router is powered on.

NVRAM (Non-Volatile Random Access Memory)

NVRAM (Non-Volatile Random Access Memory) is used to store the startup configuration. This is the configuration file that IOS reads when the router boots up. It is extremely fast memory and retains its content when the router is restarted.

Introduction to Networking

What is a Network?
     A network is a group of computers or computer like devices connected together to share the resources like file, printer, services etc. A typical network contains users working at workstations (also known as client), running clientt operating systems like Windows XP and store their files on a central server. The server computer has more resources like memory, disk space and more processing power compared with client computers. The server machine also run an Operating System, which has more precessing capabilities compared with the client machine. The server may be installed with special software, which is helps it so function as a server. The special software allows file and  print services, serve web pages, transfer emails etc.

Basic Cisco Router Configuration Commands

How to Configure a Router Hostname
To configure a name for router, use hostname command for Global Configuration mode.

 Router>enable

 Router#configure terminal

 Router(config)#hostname hour4khmer.R1

 hour4khmer.R1(config)#exit

 hour4khmer.R1#