R  E  F  E  R  E  N  C  E     C  H  A  R  T  S

RECIPE FOR SUCCESS IN CRT TESTS

#

Copyright 2003 DESCRIPTION Tony Jimenez

Do not memorize the questions & answers of my tests they are different than the real tests, use them to determine what areas you need to study more in. YOU HAVE BEEN WARNED !

WHAT IS: CSMA/CD & CSMA/CA

CSMA/CD (Carrier Sense Multiple Access/Collision Detection)

CSMA/CD is a set of rules determining how network devices respond when two devices attempt to use a data channel simultaneously (called a collision). Standard Ethernet networks use CSMA/CD. This standard enables devices to detect a collision. After detecting a collision, a device waits a random delay time and then attempts to re-transmit the message. If the device detects a collision again, it waits twice as long to try to re-transmit the message. This is known as exponential back off.
CSMA/CD is a type of contention protocol.
Contentional is defined as:

(1) Competition for resources. The term is used especially in networks to describe the situation where two or more nodes attempt to transmit a message across the same wire at the same time.

(2) A type of network protocol that allows nodes to contend for network access. That is, two or more nodes may try to send messages across the network simultaneously. The contention protocol defines what happens when this occurs. The most widely used contention protocol is CSMA/CD, used by Ethernet. Also see polling and token passing.

 

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)

When an 802,11b (WIRELESS) device intends to transmit a message, it will first sense whether another station is already transmitting (Carrier Sense). If no other transmissions are sensed, the 802,11b device will send a small request-to-send (RTS) packet to its intended recipient. If the recipient senses that the medium is clear, it sends a clear-to-send (CTS) packet in reply. Once the station wishing to transmit receives the CTS packet, it sends the actual data packet to its intended recipient. If the transmitting station does not receive a CTS packet in reply, it begins the RTS procedure over again. If an IEEE 802.11b device does sense another transmission when it wants to send, the device will apply a random deferral timer. After the timer has expired it will start sensing the medium again to see if it can start transmitting.

This protocol works fine in many networking environments, and in many cases the user of a wireless computing device may hardly notice the deferral behavior of the 802.11b device's radio. However, this free-for-all deferral behavior does not completely solve the hidden node problem, in which the stations farthest away from each other cannot 'hear' each others' packets quickly enough, because the time it takes for a packet sent from one station to reach the second station is greater than the second station's wait time. In many environments this protocol is sufficient to greatly reduce collisions and somewhat increase bandwidth utilization.

WHAT IS A MAC ADDRESS
Thanks to Mr: John Sanford

The MAC address is a unique value associated with a network adapter. MAC addresses are also known as hardware addresses or physical addresses. They uniquely identify an adapter on a LAN.

MAC addresses are 12-digit hexadecimal numbers (48 bits in length). By convention, MAC addresses are usually written in one the following two formats:

MM:MM:MM:SS:SS:SS

MM-MM-MM-SS-SS-SS

The first half of a MAC address contains the ID number of the adapter manufacturer. These IDs are regulated by an Internet standards body. The second half of a MAC address represents the serial number assigned to the adapter by the manufacturer. In the example,
 

00:A0:C9:14:C8:29

The prefix: 00A0C9 indicates the manufacturer is Intel Corporation.

Why MAC Addresses?
TCP/IP and other mainstream networking architectures generally adopt the OSI model. In this model, network functionality is subdivided into layers. MAC addresses function at the data link layer (layer 2 in the OSI model). They allow computers to uniquely identify themselves on a network at this relatively low level.
 

MAC vs. IP Addressing
Whereas MAC addressing works at the data link layer (Layer 2), IP addressing functions at the network layer (layer 3). It's a slight oversimplification, but one can think of IP addressing as supporting the software implementation and MAC addresses as supporting the hardware implementation of the network stack. The MAC address generally remains fixed and follows the network device, but the IP address changes as the network device moves from one network to another.

 
IP networks maintain a mapping between the IP address of a device and its MAC address. This mapping is known as the ARP cache or ARP table. ARP, the Address Resolution Protocol, supports the logic for obtaining this mapping and keeping the cache up to date.
 

SCSI ID PRIORITY LIST

The highest-priority ID on the SCSI bus is 7, normally the SCSI Adapter.
Next in priority, from highest to lowest, are IDs 6-0
and then 15-8. So 0 has higher priority than 15.
 

REVISED IP CLASSES REFERENCE CHART
Special thanks to Mr. Santiago Martinez

NOS INTERCONNECTIVITY CHART

Windows 9x Shares

Copyright 2003, Tony Jimenez

Native Support

Copyright 2003, Tony Jimenez

Novell Netware

Copyright 2003, Tony Jimenez

Unix/Linux Shares

Copyright 2003, Tony Jimenez

Unix/Linux Printers

Copyright 2003, Tony Jimenez

LASER PRINTERS – THE PRINTING PROCESS
“CALIFORNIA COWS WILL DANCE THE FANDANGO"

#

CLEAN:

• RESIDUAL TONER IS SCRAPED WITH RUBBER BLADE & IS DEPOSITED IN DEBRIS CAVITY OR RECYCLED TO THE TONER SUPPLY AREA IN CARTRIDGE.

• ERASE LAMPS BOMBARD DRUM WITH APPROPRIATE WAVELENGTHS CAUSING SURFACE PARTICLES TO DISCHARGE INTO THE GROUNDED DRUM LEAVING DRUM WITH NEUTRAL CHARGE.

• PRIMARY CORONA WIRE APPLIES A UNIFORM NEGATIVE CHARGE TO DRUM (~ 600V, ~1000V)

• LASER WRITES A POSITIVE IMAGE ON SURFACE OF DRUM
• PARTICLES ON DRUM STRUCK BY LASER RELEASE MOST OF THEIR NEGATIVE CHARGE INTO DRUM LEAVING THESE PARTICLES WITH A LESSER NEGATIVE CHARGE.

• TONER PARTICLES NOW HAVING MORE OF A NEGATIVE CHARGE IN RELATION TO PARTICLES ON DRUM CREATING DEVELOPED IMAGE.

• TRANSFER CORONA POSITIVELY CHARGES PAPER.
• NEGATIVELY CHARGED PARTICLES LEAP FROM DRUM TO PAPER (NOT AFFIXED YET)

• HEATED “NON-STICK” ROLLER & PRESSURE ROLLER MELT THE TONER TO THE PAPER  - PERMANENTLY AFFIXING IMAGE TO THE PAPER.
• STATIC CHARGE ELIMINATOR REMOVES PAPER’S POSITIVE CHARGE SO THAT IT’S NOT ATTRACTED TO DRUM.

OSI 7 LAYER MODEL REFERENCE CHART

#

CLICK HERE FOR JAMES BOND MEETS THE OSI 7 LAYER MODEL STORY

Copyright 2003 BIT/BYTE REFERENCE CHART Tony Jimenez

BACKUP TYPES REFERENCE CHART

Copyright 2003 RAID LEVELS REFERENCE CHART Tony Jimenez

LEVEL

0

NETWORK CABLING REFERENCE CHART

TOPOLOGIES REFERENCE CHARTS

HYBRID TOPOLOGIES SUCH AS STAR-BUS & STAR-RING    (ON THE OUTSIDE THEY LOOK LIKE A STAR TOPOLOGY)

 *    STAR BUS FEATURES A PHYSICAL STAR & A LOGICAL BUS
 *    STAR RING FEATURES A PHYSICAL STAR & A LOGICAL RING

Netware Security Database & Protocols  

Copyright 2003 BOOTUP REFERENCE CHART Tony Jimenez

                  WELL KNOWN TCP PORT CHART Tony Jimenez

Copyright 2003 IEEE REFERENCE CHART Tony Jimenez

Copyright 2003 DESCRIPTION Tony Jimenez

HARDWARE RESOURCE REFERENCE CHART

MEMORY MODULE REFERENCE CHART