Apa Itu BackDoor?

Backdoor atau "pintu belakang", dalam keamanan sistem komputer, merujuk kepada mekanisme yang dapat digunakan untuk mengakses sistem, aplikasi, atau jaringan, selain dari mekanisme yang umum digunakan (melalui proses logon atau proses autentikasi lainnya). Disebut juga sebagai back door.

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Fiber Optic

Fiber Optic Technology.

 Today we talking about fiber optic..  Have Fun...

-- A fiber-optic system is similar to the copper wire system that fiber-optics is 
    replacing.

-- Difference – fiber-optics use light pulses to transmit information down fiber 
    lines(electronic pulses in copper lines).

-- There are generally five elements that make up the construction of a fiber-
    opticstrand, or cable:

1. the optic core

2.optic cladding,

3. a buffer material,

4.a strength material 

5.the outer jacket

--  The International standard for the cladding diameter of optical fibers is 125 
     microns (um).

--  The compatibility is important - it allows fibers to fit into standard connectors 
     and splices, and allows standard tools to be used throughout the industry.

--  The differences among fibers lie in their core sizes – the light carrying region
     of the fiber.

--  Standard Single-Mode fibers – are manufactured with the smallest core size, 

     approximately 8­10 um in diameter. 

--  With its greater information-carrying capacity,

 -- Single­mode fiber typically is used for :-

•           longer distance and
•           higher bandwidth applications.     

  -- Multi-Mode fibers are available in several core sizes

       - The most widely used sizes are 50 um and 62.5 um. Larger core sizes generally have greater bandwidth and are easier to couple and interconnect.

Picture show the sizes single mode and multimode.

                     p/s : That all the basic about Fiber Optic... See yAA.

                 

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Subnetting

Subnetting

A subnet allows the flow of network traffic between hosts to be segregated based on a network configuration. By organizing hosts into logical groups, subnetting can improve network security and performance.

Subnet Masking

Applying a subnet mask to an IP address allows you to identify the network and node parts of the address. The network bits are represented by the 1s in the mask, and the node bits are represented by the 0s. Performing a bitwise logical AND operation between the IP address and the subnet mask results in the Network Address or Number.

For example, using our test IP address and the default Class B subnet mask, we get:

10001100.10110011.11110000.11001000      140.179.240.200   Class B IP Address
11111111.11111111.00000000.00000000      255.255.000.000   Default Class B Subnet Mask
--------------------------------------------------------
10001100.10110011.00000000.00000000      140.179.000.000   Network Address

Default subnet masks:

• Class A - 255.0.0.0 - 11111111.00000000.00000000.00000000
• Class B - 255.255.0.0 - 11111111.11111111.00000000.00000000
• Class C - 255.255.255.0 - 11111111.11111111.11111111.00000000

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TCP/IP

TCP/IP

(Transmission Control Protocol/Internet Protocol)

TCP/IP adalah basic Communication language or protocol of the internet. TCP/IP ini digunakan sebagai protokol komunikasi dalam private network spt intranet dan extranet.. Bila computer kita tetapkan 'direct access to the internet'.. komputer kita akan copy the TCP/IP program dan computer kita boleh berkomunikasi dengan komputer laen malalui penghantaran data dan msg.. 

Two level layer TCP/IP :-

• Higher Layer(TCP) --> Manages assembling of a message or file into smaller packet.

• Lower Layer(IP) --> Handles the address part of each packet so that it gets to the night destination.

TCP/IP layer

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