Operating instructions

Layer 3 The Network layer moves packets between computers on dif
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ferent networks. Routers operate at the Network layer. IP and IPX oper
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ate at the Network layer.
Layer 4 The Tr ansport layer breaks data down into manageable
chunks. TCP, UDP, SPX, and NetBEUI operate at the Transport layer.
Layer 5 The Session layer manages connections between machines.
NetBIOS and Sockets operate at the Session layer.
Layer 6 The Presentation layer, which can also manage data encryp
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tion, hides the differences between various types of computer systems.
Layer 7 The Application layer provides tools for programs to use to
access the network (and the lower layers). HTTP, FTP, SMTP, and POP3
are all examples of protocols that operate at the Application layer.
overclocking To run a CPU or video processor faster than its rated speed.
P1 connector A type of connector used to provide power to ATX mother-
boards.
P4 12V connector A type of connector used to provide additional 12-volt
power to motherboards that support Pentium 4 and later processors.
P8 and P9 connectors A type of connector used to provide power to AT-style
motherboards.
packet Basic component of communication over a network. A group of bits
of fixed maximum size and well-defined format that is switched and transmit
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ted as a single entity through a network. It contains source and destination ad
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dress, data, and control information.
paragraph A unit of 64 binary bits; eight bytes. Not a commonly used term.
parallel port A connection for the synchronous, high-speed flow of data
along parallel lines to a device, usually a printer.
parity A method of error detection where a small group of bits being trans
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ferred are compared to a single “parity” bit that is set to make the total bits odd
or even. The receiving device reads the parity bit and determines if the data is
valid based on the oddness or evenness of the parity bit.
GLOSSARY 49
Passport / Mike Meyers‘ A+ Certification Passport / Meyers / 226308-3 / Glossary
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