Networking Basics & LAN Flashcards
Host
Local Host
Remote Host
Host: Any computing device connected to a network.
Local Host: Your own computer/device.
Remote Host: Another computing device on the network or reachable beyond the network.
Web Server
+
2 Web Server Programs
Stores files that make up a website.
Uses server programs to store/share the data.
Programs:
Apache HTTP
IIS (Microsoft Internet Information Services)
File Server
A networked host that enables you to access a bunch of files/folders.
Mail Server
A networked host that allows access to email.
Resource
Anything one computer might share with another.
Legacy System
An old method, technology, computer system, or application that is outdated but still in use.
Embedded System
A computer system that has a dedicated function with a larger mechanical or electrical system.
NIC
Network Interface Controller (C used to be Card):
Define/label a machine on a network.
Breaks files into smaller data units to send across the network. Reassembles units it receives to whole files.
Frames
(Packets are included in frames)
+ 4 Parts
Discrete chunks of data that NICs move from one devices to another.
4 Parts:
MAC address of network card receiving data
MAC address of network card sending data
Data itself
Data check with algorithm (CRC = Cyclic Redundancy Check)
MAC Address
Media Access Control:
48-bit binary number (281 Trillion + in existence)
Total of 12 hexadecimal characters
Some NICs allow MAC addresses to be changed (rare)
Hexadecimal
One hex character represents a string of 1s and 0s.
C = 1100 2 = 0010 9= 1001
1 - 9 & A - F
Ethernet (General)
A series of standards that defines everything necessary to get data from one computer to another.
Mid 1970s by Intel, Xerox, Digital Equipment Corp
Hundreds of distinct improvements: “Flavors”
Ethernet Speed Categories (Main 3)
10BaseT = 10Mbps 100BaseT = 100Mbps 1000BaseT = 1000Mbps or 1Gbps (Gigabit)
Star Bus Topology
A central box (switch) that each individual host connects to.
“Star” comes from the idea of the switch being in the center and the wires to computers spreading out like a star.
Switch
Provides a common point of connection for network devices.
Wide variety of ports; each port is treated as a separate network.
“Smart Repeater”: Memorize MAC of all connected devices & only sends repeated signals to the correct host. (Unlike Hubs)
Hub
A basic “repeater”:
Anything sent in one port goes to all other ports.
Replaced by switches.
Segment
A connection between a computer & switch.
Ethernet segments = 100m max
Splitters wouldn’t work with segments (negative effect on signal quality).
Switch wouldn’t recognize which host is sending/receiving.
UTP
Unshielded Twisted Pair:
Specified cabling for 10/100/1000BaseT
AWG 22-26 gauge wire twisted together into color-coded pairs.
Come in categories that define transfer speed.
UTP Categories
Established by ANSI/TIA
Cat 1: Telephone line Cat 3: 10Mbps Cat 5: 100Mbps Cat 5e: Enhanced to handle 1000Mbps Cat 6: Gigabit @ 100m (10Gbps = 55m) Cat 6a: 10Gbps @ 100m Cat 6e: nonstandard; means Cat 6 or Cat 6a Cat 7: 10Gbps @ 100m + shielding to reduce noise (^^^ NOT an ANSI/TIA standard ^^^)
Solid Core UTP
Uses a single solid wire.
Better conductor.
Stiff, can break if handled too often/roughly.
Horizontal cabling should always be solid core.
Stranded Core UTP
Each wire is a bundle of tiny wire strands.
More durable for handling.
Not as good of a conductor as solid core.
STP
Shielded Twisted Pair:
Twisted pairs of wires surrounded by a shielding to protect from EMI.
Useful in locations with excessive electronic noise.
Ethernet Types w/UTP Categories
10BaseT = Cat 3 at least; typically Cat 5 100BaseT = At least Cat 5 1000BaseT = Cat 5e or higher
RJ-45
Registered Jack 45
Standard for UTP connectors (4 pairs)
Wider than RJ-11 (telephone jack)
T568A vs. T568B
RJ-45 standards (color coding is different)
Hint: orange & green switch! everything else stays
T568A:
G-W, G, O-W, BL, BL-W, O, BR-W, BR
T568B:
O-W, O, G-W, BL, BL-W, G, BR-W, BR
RJ-11
Standard for telephone lines & telephone-based internet.
Plenum & Plenum Problem, & Plenum-Rated Cables
Plenum: the space in the ceiling under the floors, in the walls, through which cable runs.
Plenum Problem: heat can melt PVC from cables, creating noxious fumes that could spread throughout the building.
Plenum-grade cabling: Cabling with a fire-retardant jacket
Crossover Cable
A standard UTP cable with one RJ-45 connector using T568A, the other using T568B.
Reverses the signal between sending & receiving wires (similar to a hub/switch)
Quick way to connect 2 computers directly.
Fiber Optic Cabling (General)
Uses light instead of electricity.
Immune to electrical problems.
Signals travel much farther than UTP (2000m+)
Half-duplex
2 types of light: Regular & Laser
Fiber Optic Connectors
ST Connector: Round
SC Connector: Square
LC Connector: Double square-shaped
(Designed to support two fiber cables in one to compensate for issue with half-duplexing)
Half-Duplex
Data flows only one way (hence the need for 2 cables in fiber optics)
Also, hence the use of the LC connector.
Network Fiber Optics (Light Type)
Network fiber optics use LED light signals.
Multimode Fiber Optic Cabling
Slower than single-mode.
Transmits multiple light signals at the same time.
Each signal uses different reflection angles
(Best for short distances; will disperse if too long)
600m max length (generally)
Single-Mode Fiber Optic Cabling
Faster than multimode
Use laser light: high transfer rates over long distances.
Rare, niche use.
Coaxial Cabling
Consists of a center cable (core) surrounded by insulation.
Covered with a shield of braided cable.
Core carries signal; shield eliminates interference.
Tops off at 100Mbps
RG-59
Coaxial Cabling Rating:
Low bandwidth & lower frequency applications
(Analog video & CCTV installations)
75 ohm impedance
Thinner than RG-6; doesn’t carry signal as far
RG-6
Coaxial Cabling Rating:
High-bandwidth & higher frequency applications
(Internet, cable TV, Satellite TV)
75 ohm impedance
Heavier gauge than RG-59
(Thicker insulation & better shielding)
Coaxial Connectors
BNC Connector:
Quarter-twist connector (uncommon)
F-Type Connector: Screw connector (common: cable modems/TVs)
LAN
Local Area Network:
Group of computers located physically close to one another (no more than a few hundred meters)
Almost always a broadcast domain.
Broadcast Domain
Group of computers connected by one or more switches.
Ethernet over Power (EoP)
Uses specialized bridges that transfer ethernet signal through the powerline.
Bridge
A device that connects dissimilar network technologies that transmit the same signal.
Connects two LANs and controls data flow between them.
Only has 2 ports, as opposed to a switch, which has many.
Structured Cabling
Cabling system by ANSI/TIA that give pro installers detailed standards on every standards on every aspect of a cabled network.
(type of cabling, running cable into walls, position of wall outlets, etc.)
Purpose of Structured Cabling
To create a safe, reliable cabling infrastructure for all devices that may need interconnection.
(Useful for telephone networks & video conferencing as well)