CompTIA Network+ Notes

8/9/2019 CompTIA Network+ Notes

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CompTIA Network+ (N10-005)

LAN / WAN

LAN (Local Area Network)

data network restricted to a single geographic location

encompasses a relatively small area

(examples) office, building, school, etc.

WAN (Wide Area Network)

spans more than one geographic location location

connects separate LANs

MAN (Metropolitan Area Network)

WAN that is confined to a certain geographic area

(example) university campus, city, etc.

Network Models

Peer-to-Peer

decentralized network model

no centralized storage of data or control over the sharing of files or

resources

each computer serves as its own client and server

no admin is needed

no more than 10 computers should be connected

Client / Server

centralized model

services are managed from a central location

user management

security

backup procedures

size is only limited by server size

The role of the client computer is to request the data from the server

Centralized Computing model

one system provides both the data storage + processing power for client

systems

Distributed Computing model

processing power distributed between client systems and server

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Wired Network Topologies

Topology

physical topology - networks physical layout of computer cables/devices

logical topology - the way in which the network appears to the devices thatuse it

Bus

all computers are connected to a single cable serving as the backbone

T Connectors- used for systems to connect to backbone

each end of the bus must be terminated

if not, it disrupts data transmissions

one end also must be grounded

a hub or switch is not needed

Ring

it is logical

data travels in a circular fashion

hub or switch is not needed

if single system on ring fails, whole network fails

when computers are added or removed from network, disruption occurs

MSAU (Multi Access Unit) - performs the token circulation

Star

all computers connect to a central device (hub or switch)

each connected device requires a single cable to be connected

creates a point-to-point (PtP) connection

easiest to expand and add devices

most popular

Mesh

each computer on network connects to every other computer

point-to-point (PtP) with each computer

provides high level of redundancy

better fault tolerance

to calculate number of connections in a mesh

y(y-1)/2 y = # of computers | 5 computers = 10 connections

Hybrid

combines different kinds of topologies

PtP (Point-to-Point)

2 computers connected directly to each other

no need for a central device

can be created using a crossover cable

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(example) computer connected to printer

PtMP (Point-to-MultiPoint)

looks like a star network, but without a central connection

has a single system acting as common source through which all

members are connected

had device that provides a path to any or all connected devices

MPLS (Multiprotocol Label Switching)

technology designed to speed up traffic flow

creates a channel/path for packets to reach destination

each packet is assigned a label

the label associates it with the specific path

all packets with the same label use the same path

known as LSP (Label Switched Path)

eliminates need to check the packet for forwarding at each hop

reduces need to check routing tables

Wireless Network Topologies

Infrastructure

used to extend a wired LAN to included wireless devices

wireless devices communicate with the wired LAN through the WAP

commonly used to extend a wired LAN to include wireless devices

WAP forms a bridge between a wireless and wired LAN

WAP must stay connected to the wired network

there can be several wap to cover a large area, or a single wap for smaller

areas

Ad Hoc

devices communicate directly between themselves without using an

access point

connect a small number of computers

does not use an AP

Virtual Networks

VPN (Virtual Private Network) a secure communication channel across the public network, enabling

access for a client to a private network

such as a company's internal network

provides point-to-point dedicated link between two points over a public IP

network.

establishes connection between remote clients and a private network

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Components of VPN Connection

VPN client - computer that initiates the connection

VPN server - authenticates connections

Access method - public network, sometimes a private intranet

VPN protocols

PPTP (Point-to-Point Tunneling Protocol) L2TP (Layer 2 Tunneling Protocol)

enables authentication and encryption to protect data from

general public

LAN-to-LAN

when a VPN is used to connect one private LAN to another

VLAN (Virtual Local Area Network)

used for network segmentation

Logical group of workstations

segmentation is used for several reasons

security, organization, performance a group of connected computers that act as if they are on their own

network segments

VLan Membership

Protocol-based = assigned by their protocol in use and the Layer 3

Port-based = the ports of the switch are configured to belong to the

various VLAns

MAC address-based = assigns membership according to the

workstations MAC address

Subnet-based = the subnets of the IP addresses of individual

computers are used to identify the VLAN to which it belongs

{ OSI +TCP/IP Models + Network Protocols }

OSI Layers

(Open System Interconnection)

Describes a network architecture that enables data to be passed between

computer systems

Layer 1 - Physical Layer

Layer 1 Devices = NIC, Hub, Repeater, network cabling

Defines the physical structure of the network and the topology

Hardware

type of cable, connector, pinout format for cables

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Topology

ring, mesh, star, bus

defines voltage, frequency of signals, speed and bandwidth, maximum

distance, multiplexing strategy

Common problems = NIC failure or not properly seated, faulty hub or

repeater, cut or damaged network cable bits - the logical grouping of data at the Physical Layer

Layer 2 - Data Link Layer

Layer 2 Devices: Bridge, Switch, NIC, AP

Receives and puts data on the cable

Provides error detection and correction

Two sublayers: MAC and LLC

responsible for getting data to Layer 1 (Physical Layer)

getting data on or off the cable responsible for error detection, error correction and hardware addressing

When sending data: groups bits into packets for transmission over

network

When receiving data: takes packaged data and breaks it into individual bits

for Layer 3

MAC Layer

(Media Access Control Layer)

MAC address is defined at this layer

(example) 00:A0:C9:14:C8:29 First half of MAC address is ID number of the NIC

manufacturer

Second half is the unique number assigned to the NIC by

the manufacturer

LLC Layer

(Logical Link Control Layer)

responsible for flow-control

Will make sure not too much data is being sent waiting

period for data is not too long data that was damaged gats

re-sent

CRC (Cyclic Redundancy Check)

provides error detection by using a calculated value

is a value that is added to the packet by the LLC on the

sending end

its recalculated on the receiving end and compared to the

original if matches, data is ok

frames / packets- the logical grouping of data at the Data Link Layer

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Layer 3 - Network Layer

Layer 3 Devices: Switch, Router

Handles the discovery of destination systems and addressing

Manages network addresses

when Receiving Data

reads data packets that are passed from Layer 2

Checks packets for destination address

Compares destination address to its own IP address to determine

if the packet should be passed up to Layer 4

when Sending Data

receives data from layer 4

adds its own IP address to the packet as the source address

protocols at Layer 3 are responsible for route selection Datagrams / Packets - the logical grouping of data at the Network Layer

Layer 4 - Transport Layer

Provides connection services between sending and receiving devices

Ensures reliable data delivery

correct sequence, without errors, fastest and most efficient flow

rate possible

Manages flow control through buffering or windowing

Provides segmentation, error checking, and service identification

Segmentation - blocks of data need to be broken into packets ofmanageable sized for the lower layers (and opposite for upper layers)

data is transferred over network in two ways:

UDP - connectionless

excellent for data that must be delivered asap

(examples) video, walki-talkie radio, etc.

no confirmation

TCP - connection-oriented

connection is established before communication begins

data is delivered in sections

confirmation system is used to make sure the data was

delivered

Data flow control

Buffering - data is temporarily stored and waits for the destination

device to become available

Windowing - data is sent in groups of segments

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Layer 5 - Session Layer

Synchronizes the data exchange between applications on separate

devices

Layer 6 - Presentation Layer Serves as translator between Layer 7 and Layer 5

Translates data from the formated used by applications into one that can

be transmitted across the network

Formats data from Layer 7 into format that can be sent over network

Handles encryption and decryption of data

encryption - scrambling of data so that it cant be read by anyone

other than the intended recipient

Provides compression and decompression functionality

Layer 7 - Application Layer Provides access to the network for applications

Take requests and data from the users and pass them to the lower layers

of the OSI model

provides full end-user access to network services

this is where bits (0s and1s), MAC and IP addresses are translated so ppl

can understand it

TCP/IP Model

TCP/IP Model OSI Model

4. Application Layer 7. Application Layer

6. Presentation Layer

5. Session Layer

3. Transport Layer 4. Transport Layer

2. Internet Layer 3. Network Layer

1. Network Interface

Layer

2. Data Link Layer

1. Physical Layer

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Protocol Ports

Protocol Port

FTP 20,21

SSH 22

Telnet 23

SMTP 25

DNS 53

DHCP (BOOTP server) 67

DHCP (BOOTP client) 68

TFTP 69

HTTP 80

POP3 110

NNTP 119

NTP 123

IMAP4 143

SNMP 161

HTTPS 443

RDP 3389

Protocols

IP (Internet Protocol)

connectionless responsible for addressing and routing of packets between computers

used to move data around a network

Layer 3 - Network Layer

TCP (Transmission Control Protocol)

Layer 4

connection-oriented

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responsible for guaranteed delivery of data

offers flow control, sequencing, retransmission of dropped packets

TCP three-way handshake

1. sends message called a SYN to the target host

2. host sends back acknowledgement, ACK

3. responds to the acknowledgement with another ACK breaks data into manageable packets

tracks info such as source & destination of packets

able to reroute packets

UDP (User Datagram Protocol)

connectionless

Layer 4 - Transport Layer

DHCP (Dynamic Host Control Protocol)

Gives out IP addresses

FTP (File Transfer Protocol)

used for transferring files between two remote systems uploads and downloads files to and from remote host

basic file-management tasks

Layer 7 - Application Layer

port 21 is mostly used in modern implementations, not 20

SFTP (Secure File Transfer Protocol)

securely uploads and downloads files to and from remote host

based on SSH security


TFTP (Trivial File Transfer Protocol)

connectionless Layer 7 - Application Layer

SMTP (Simple Mail Transfer Protocol)

HTTP (Hypertext Transfer Protocol)

retrieves files from a web server


HTTPS (Hypertext Transfer Protocol Secure)

secure protocol for retrieving files from a web server


POP3 / IMAP4

retrieves mail

cannot send mail


Telnet

enables sessions to be opened on a remote host

Layer 7

SSH (Secure Shell)

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port: 22

enables secure sessions to be opened on remote host

or secure alternative to Telnet

Layer 7

ICMP (Internet Control Message Protocol)

used for error reporting, flow control, route testing Layer 3

ARP (Address Resolution Protocol)

resolves IP addresses to MAC addresses to enable communication

between devices

Layer 2

RARP (Reverse Address Resolution Protocol)

resolves MAC addresses to IP addresses

NTP (Network Time Protocol)

communicates time synchronization information between devices

Layer 8 NNTP (Network News Transport Protocol)

SCP (Secure Copy Protocol)

LDAP (Lightweight Directory Access Protocol)

Accesses and queries directory services systems

Layer 7

IGMP (Internet Group Management Protocol)

TLS (Transport Layer Security)

SIP (Session Initiated Protocol)

RTP (Real-time Transport Protocol)

for transporting real-time data often used with VoIP

Layer 7

DNS (Domain Name Service)

resolves hostnames to IP addresses

before DNS the Internet used to use a text file called HOSTS to perform name

resolution

DNS Clients

AKA resolvers

systems that ask DNS servers for a hostname-to-IP address mapping

DDNS (Dynamic DNS)

newer system that enables hosts to be dynamically registered with the

DNS server

DNS namespace

space that has logical divisions hierarchically organized

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.com .edu .uk .de

FQDN (Fully Qualified Domain Name)

domain name along with subdomains

(example) www.comptia.org

www = host

comptia = second-level domain .org = top-level domain

reverse lookup

IP address-to-hostname

accomplished by using Pointer Records (PTR)

DNS Records

MX (Mail Exchange)

stores info about where mail for the domain should be delivered

AAAA (IPv6)

Stores info for IPv6 addresses it is commonly used to map hostnames to an IP address for a host

CNAME (Canonical Name)

stores additional hostnames, or aliases, for hosts in domain

give single computer multiple names (aliases)

PTR (Pointer)

used to perform a reverse DNS lookup

name is returned when query originates with an IP address

SOA (Start of Authority)

record of info containing data on DNS zones and other DNS

records WINS (Windows Internet Name Services)

can be used to resolve NetBIOS names to IP addresses

SNMP

(Simple Network Management Protocol)

protocol that makes NMS possible

NMS = Network Management System

used for monitoring information on a network

performed through a software component called an agent

monitor any device that is SNMP capable

computers, printers, routers, servers, etc.

MIB

databases of info to define what parameters are accessible, read-only and

can be set

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Communities - logical groupings of systems. If device is part of a community tit

communicates only with other devices within it

traps - captures snapshot data of the system

could be system errors, resource info etc.

SNMPv2

enhancements on v1 includes bit strings, network addresses and counters

SNMPv3

better security: authentication + encryption

DHCP

scopes - ranges of IP addresses

lease - address that is assigned for a predetermined amount of time

reservation - when a specific address assigned to a client. IP always remains the

same.

exclusion - certain IP addresses that are not to be given out

DHCP is protocol-dependent, not platform-dependent.

Can provide DNS suffixes to clients

DNS Suffixes - define DNS servers to be used and the order in which to

use them

Process

1. Client broadcasts dhcpdiscover packet

2. DHCP picks up the packet, compares request with scopes it has

defined

3. DHCP sends address + lease duration through dhcpofferpacket

4. Client receives offer, determines if it is suitable

5. Client sends back dhcprequestpacket

6. DHCP finalizes and sends dhcpack packet of acknowledgement

{ Addressing + Routing }

IP Addressing

IP Address - defines the number of the network and the number of the node

Subnet Mask - defines which portion of the IP address refers to the network

address and which refers to the node address

Default Gateway - path out of the network for a given device

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if system is not configured with any static routes or a default gateway, it is

limited to operating on its own network segment

Subnetting = increased number of network IDs decreases number of node IDs

Unicast = single address is specified. Data is delivered to a specific node.

Broadcast = message goes to everyone on the network

Multicast = a single source sends data to multiple destination addresses CIDR (Classless Interdomain Routing)

method to assign addresses outside the standard ABC classes

BOOTP = used to obtain info needed to connect to the network

System that does not support APIPA will assign itself an IP address of 0.0.0.0.

IPv4 IPv6

Loopback Address 127.0.0.1 ::1

Network-wide addresses Public IP ranges

Class A: 1.0.0.0 - 126.255.255.255

Class B: 128.0.0.0- 191.255.255.255

Class C: 192.0.0.0 - 223.255.255.255

Global Unicast Addresses

Private network addresses Class A: 10.0.0.0 - 10.255.255.255

Class B: 172.16.0.0 - 172.31.255.255

Class C: 192.168.0.0 - 192.168.255.255

Site-local Address ranges

FEC0::

Autoconfigured addresses APIPA: 169.254.0.1 - 169.255.254.0 Link-local Addresses

FE80::

NAT (Network Address Translation)

Enables a LAN to use a different set of IP addresses for internal traffic and

another for external

computers can hide behind a single IP address

one registered IP address acts as the gateway between the internal and external

networks

to the remote host, the request looks like it is originating from a single address

system performing NAT function keeps track of who asked for what and makes

sure data is returned PAT (Port Address Translation)

a service of NAT

SNAT (Static NAT)

maps a private IP to a static unchanging public IP address

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Routing

Default Gateway

is the routers IP address

help forward the packet to its destination network

provides route for destinations outside the local network gateway can be a device, system or application that translates data from

one format into another

Routing Table

Destination = the host IP address

Network Mask = the subnet mask value for the destination

Gateway = Where the IP address is sent

Interface = address of interface used to send the packet of destination

Metric = measurement of directness of a route, the lower the metric the

faster the route

Hop Counts - number of hops necessary to reach node. if it counts

to infinity it means route is unreachable.

MTU (Maximum Transmission Unit) - defines largest data unit that

can be passed without fragmenting

Bandwidth - maximum packet size permitted for transmission

Costs - the lower the cost, the more that route should be favored

Latency - amount of time it takes for packet to travel from one

location to another

routers get info for the routing table in two ways: static routing & dynamic routing

Static Routing is manually entered into the routing table

route add= command used to add a static route to the routing table

route add -p = makes the static route persistent

Dynamic Routing

routers pass info about themselves to other routers so that they can build routing

tables

uses 2 protocols: Distance-Vector Routing & link-state

Distance-Vector Routing

each router on network communicates all the routes it knows about to the

routers to which it is directly attached

RIP

limited to a max of 15 hops

requires updates every 30 seconds

no authentication

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RIPv2

authentication

limit 15 hops

BGP

pick best available route

EIGRP uses neighbors to help determine routing table

keeps copy of their routing info

find best possible route

using DAUL (Diffusing Update Algorithm)

Convergence - time for the routers to detect and accommodate a change

Routing Loops - occur when routing tables on the routes are slow to

update

Split Horizon - to prevent routing loops

Poison Reverse - to prevent routing loops

Next Hop- the next closest router that a packet can go through

Link-State Routing

build a map of entire network and then holds the map in memory

updates occur less frequently

OSPF (Open Shortest Path First)

least-cost path

used in medium to large enterprise networks

IS-IS

discovers shortest path for data to travel using Shortest Path First

algorithm (SPF) in large ISP networks

STP (Spanning Tree Protocol)

Actively monitors the network and shuts down redundant links to prevent

switching loops

Switching loops - caused by having more than one path between two switches in

a network

STP prevents this

STA is the algorithm STP uses to correct loops

BPDU (Bridge Protocol Data Unit)

used to identify the status of ports and bridges across the network

redundant paths and loops can be avoided with ports by:

blocking | disabled | forwarding | learning | listening

Trunking

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trunking is the use of multiple network cables

Link Aggregation is another name for it

the process of transferring VLAN traffic between multiple switches

to connect the two (or more) switches together

configure a port on each switch as a trunk port

connect two switches via trunk ports IEEE 802.1Q is the trunk standard that now allows you to connect switches from

different manufacturers

Port Mirroring

monitors network traffic

enables administrators to monitor the traffic outbound and inbound to the switch

{ Components + Devices }

Bridges

Connects LANs to reduce overall network traffic

enables data to pass through it or prevent data from passing through it

done by reading MAC address

divide larger networks into smaller sections

sits between 2 physical network segments and manges flow of data

between them

can elect to forward the data or block it from crossing can connect two physical LANS into a larger logicalLAN

learning bridges - can build a list of MAC address

Bridge Placement

80% of data should be local

20% should be for other side of bridge

Bridge Loops

when more than one bridge is implemented on network

Spanning Tree Protocol assigns value to bridge to be used to control

bridge-learning process

Transparent Bridge

devices on network dont see it

used to segment a network

reduces number of collisions and traffic

blocs or forwards data based on the MAC address

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Source Route Bridge

used in token ring networks

Translational Bridge

converts one networking data format to another

NIC

Link Light - indicates whether a network connection exists

Activity Light - indicates activity, should flicker

Switches

Cut-through - packet just gets forwarded, no error check

store-and-forward - error checked before forwarded

Fragment Free - faster at forwarding + checking

CSU/DSU

translates digital signals used on a LAN into those used in WAN

Modems

modulate/demodulate

translates signals from analog to digital

translates signals from digital to analog

Media Converter interconnects older technologies with newer ones

a hardware device

connects newer Gigabit Ethernet technologies with older 100BaseT networks or

older copper standards with fiber

{ Specialized Network Devices }

Bandwidth Shaper

Monitors and shapes

identifies where bandwidth usage is high and the time of day

shape bandwidth usage

Traffic Shaping

used to control bandwidth usage on the network

control who uses bandwidth, for what purpose and what time

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Content Filter

controls what a user is allowed to pursue

block access to certain websites or a user

Load Balancer

workload is distributed between several servers

increases redundancy and data availability

increases performance by distributing workload

can be either a hardware device or software

Multilayer Switches

Operates as a router + switch Layer 2 + Layer 3

Content Switch

identify and forward data by its port and application

help distribute the load

1. examines the network data it receives

2. decides where the content is intended to go

3. then forwards it

Proxy Server usually part of firewall system

a server that sits between a client pc and Internet

sends request as if it originated the request

as if the request came from the proxy, not the client cp

retrieves info and returns it to the client

Caching

makes a copy of all or part of the page in its cache

when page is requested again, proxy server answers the request from thecache

allows network admins to filter client requests

can block access to certain websites

ACL - a list of allowed or unallowed websites

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Virtual Servers

a single server can host multiple logical machines

Virtual Switches

allows multiple switches to exist on same host

used with VLAN implementations

can provide a direct challenge to the virtual Ethernet adapters for config info

Open vSwitch- an open source virtual switch

Virtual PBX

(Virtual Private Branch Exchange)

phone system

handles features such as call routing, voicemail, faxing.. etc.

a service that is contracted out to a vendor routed through a vendor

they are responsible for the equipment and software

VoIP is used for routing the voice traffic

Onsite / Offsite

offsite- data center hosted elsewhere and remotely accessed

another vendor is responsible for maintaining hardware and software

(example) Electronic Monitoring Company has data come in to servers in

Colorado, but operates work with the data from workstations in Indiana

NaaS (Network as a Service)

vendors offer an entire network

freeing a company from administration

similar to Saas (Software as a Service)

OpenStack - is an open source NaaS implementation

{ Installation + Configuration }

Demarcation Point

point where the service provider stops being responsible for the line and it

becomes the technicians responsibility

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Packet Switching

messages are broken into smaller pireces calledpackets

each packet is assigned source, destination and intermediate node address

most popular switching

1. Virtual-Circuit switching uses a logical connection between the source and the destination device

2. Datagram Circuit switching

packets are independently sent and can take different paths through the

network to reach their intended destinations

packets can be routed around network congestion

Circuit Switching

offers a dedicated transmission channel that is reserved until it is disconnected

when transmission is complete, channel is closed

after physical connection is established, it is unavailable to any other sessions

until transmission completes

ISDN

used to transmit voice, video and data

uses public network, requires dial-in access

can be used for circuit-switching connections

can be used for packet-switching connections

used with copper/fiber-optic

leased from a service provider

requires dial-up access

ISDN is faster than PSTN

PSTN - used when little traffic is sent over a line. most cost-effective. limited to 56

Kbps

requires dial-up access

D Channels - carries signaling information

B Channel - carries the data

BRI ISDN - uses two B+1 D channels

PRI ISDN - uses 23 B+1 D channels

T-Carrier

used to create point-to-point network connections for private networks

uses in circuit switching

leased from telephone companies

T1

1.5 Mbps

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synonymous with DS1

T3

4.7 Mbps

synonymous with DS3

Fractional T - leasing portions of a T-carrier service

ATM

uses fixed cells that are 53 bytes long

1.544 Mbps to 622 Mbps

Cell switching

uses SVC + PVC

Frame Relay

operates at Layer 1 + Layer 2

a packet-switching technology

PVC (Permanent Virtual Circuit)

a permanent dedicated virtual link

SVS (Switched Virtual Circuit)

represents a temporary virtual circuit established and maintained

only for the duration of a data transfer sesion

SONET/OCx (Synchronous Optical Network)

defines synchronous data transfer over optical cable

delivers voice, data and video

OCx (Optical Carrier)

represent the range of digital signals that can be carried in a SONET

fiber-optic networks

each level defines the speed at which it operates

SDH - is the European counterpart of SONET

DWDM works with SONET/SDH

PON (Passive Optical Network)

services a number of different locations

uses unpowered optical splitters to split the fiver

DSL Internet Access

uses a standard phone line to provide high-speed Internet access

ADSL

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provides a high data rate in only one direction

fast download speeds but slower upload speeds

designed to work with existing POTS service

best for home-use

most common

1st Channel - responsible for analog traffic

2nd Channel - provides upload access

3rd Channel - used for downloads

HDSL

provides bidirectional high data service

VHDSL - faster version

SDSL

same speeds for both uploads and downloads

cannot share a phone line

Troubleshooting DSL

Physical connections

NIC

Drivers

protocol Configuration

DSL LEDs

Cable Internet Access

Cable Modem

uses coax connection for connecting to the providers outlet

uses UTP connection for connecting directly to a system or to a hub or

switch

uses MDI-X

shares available bandwidth with everyone else in cable area

Satellite

One-way Satellite system

requires a satellite card and satellite dish installed at users site outgoing requests sent through phone line

inbound traffic returns on satellite link

Two-way Satellite System

provides data paths for upstream and downstream data

Rain Fade = signal loss due to moisture interference

Latency = time lapse between sending info and time to return

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Line of sight = path between satellite dish and satellite

Cellular

LTE

4G upload speed = 50 Mbps

download speed = 100 Mbps

WiMax

4G

upload speed: 56 = Mbps

download speed = 1 Gbps

HSPA+

3G

{ Cabling + Wiring }

Broadband vs Baseband Transmissions

Baseband

digital signals over a single wire

bidirectional, but not at the same time

TDM (Time Division Multiplexing)

divides a single channel into time slots

Broadband use analog transmissions

FDM (Frequency Division Multiplexing)

used to create multiple channels

BPL (Broadband over Power Lines)

transmit data over lines used for electrical power

IEEE 1901 = for high-speed communication devices

IEEE 105 = for hybrid home networks

bpl = HomePlug

Simplex / Half Duplex / Full Duplex

Simplex = one-way communication of data through the network

Half-duplex = transmitting + receiving but not at same time

Full-Duplex = simultaneously transmit and receive

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Noise

any undesirable influence that degrades or distorts the signal

EMI (Electromagnetic Interference)

waves that emanate from electrical devices or cables

RFI (Radio Frequency Interferences) caused by radio waves

Crosstalk

when two wires near each other and the signal from one infringes on

signal traveling through the other wire

Attenuation

loss of signal strength as it moves farther from source

Latency

amount of time it takes electrons to move through the wire

Cabling

Twisted Pair

STP (Shielded Twisted Pair)

Max Length = 100 meters

Foil around each pair - prevents EMI

less susceptible to interference

are larger than UTP and less flexible due to shielding

UTP (Unshielded Twisted Pair)

Susceptible to interference (fluorescent light)

4 pairs of twisted wires, 8 wires total

Categories (max Length: 100 meters 328 feet) CAT1 Standard telephone cable

CAT3 10 Mbps

CAT4 16 Mbps

CAT5 100 Mbps

used with RJ-45 connectors

CAT5e 1 Gbps

CAT6 10 Gbps (55 meters)

CAT6e 10 Gbps (100 meters)

Plenum - area above suspended ceiling fire resistant cable

Coax Cable

Single core of copper

Central conductor wire surrounded by insulation which is surrounded by a

braided metal shield

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Used for Cable Modems, ISP (Internet Service provider), Cable TV and

Modem-based internet connections

All coax cables have an RG (Radio Grade) rating

The exam includes RG-6 and RG-59 (most commonly used)

both are rated at 75 Ohms

RG-49 Thinnet / 10Base2

Carries 10 Mbps of Ethernet data

Max length: 185 meters

50 ohm impedance

RG-6

Thicknet / 10Base5

10 Mbps

50-MHz or higher


75 ohm impedance RG-6/U

used for cable TV

75 ohms of impedance


Connectors:

F-type (most common)

BNC (older) screw by spinning on

75 oh impedance

Note: Baseband (Base) - only one signal at a time is sent onto the

network medium

Broadband - multiplexes the signals to allow multiple signals on

the medium

Fiber-Optic Cable

shoots pulses of light

Multi-Mode

larger core, 50 - 115 microns in diameter

62.5 microns - most common

10 Gbps

500-600 meters

uses LED (Light Emitting diodes) to send light signal

multiple sets of data at a time

Single-Mode

Narrow core, less than 10 microns

Data travels over single path

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Provides highest bandwidth and longest distance

1 Tbps

uses Laser to send light signal

3000 meters - 40 km

Throughput - up to 100 Gbps

Plenum

area above suspended ceiling

used to run network cables

plenum cables create low smoke and low toxic fumes

Coaxial Connectors

BNC

F-Connectors

Twisted Pair Connectors

RJ-45

Fiber Optic Connectors ST

SC

LC

Wiring Standards

T568-A

1. Green-White

2. Green

3. Orange-White

4. Blue

5. Blue-White

6. Orange

7. Brown-White

8. Brown

T569-B

(preferred standard)

switch up green with orange

if needed to connect T568-A with type B, use a crossover cable

Crossover Cable

A standard network cable is wired using the T568-A or B on each end

(straight-through wiring)

Crossover cable has the A on one connector and B on the other side.

Rollover Cable

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Cable that is used to connect to a Cisco Router for Configuration

aka Yost Cable

Almost 100% unique to Cisco routers

called rollover because the pinouts on one arc are reversed on the other end

as if the wire has been rolled over and you are viewing it from the opposite

side

Loopback Cable

used when troubleshooting a network issue

used to identify if the problem is with the NIC

tests NIC circuitry that sends and receives data within the NIC

does not check the actual connection pins

Network Cross-Connects

Horizontal cabling

cabling that runs from work area to Telecom Room

Run - a single piece of cable running from the work area to Telecom room

Patch Panel

makes reconfiguring/moving cables safe and easy

the front of a patch panel has female connectors (ports) for network cables

The back of patch panel has permanent connections

the horizontal cable runs are connected here

Data flow can be changed by rearranging the patch cables plugged into the front

of the patch panel

MDF (Main distribution Frame)

houses the network and telphone equipment that connects to the outside world

IDF (Intermediate Distribution Frame)

where all the horizontal runs come together

Demarcation

a location in the building where a connection is made to the outside world

for telephone & computer networks

everything inside the demarcation point is the responsibility of the network

administrator or the company

everything outside of demarcation point is the responsibility of service provider

NIU (Network Interface Unit)

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piece of equipment that established the demarcation point between your

network and the service providers network

First piece of equipment that is located inside the demarc point

marks point where technicians responsibility begins with the network

unit that allows network to interface with outside world

Demarc Extension cable used to connect to the NIU

for computer networks, 1st device inside the NIU is a powerful switch

Nicknames for NIU

Smart Jack

NIB (Network Interface Box)

NID (Network Interface Device)

CSU / DSU

used when troubleshooting a network issue

used to identify if the problem is with the NIC

tests NIC circuitry that sends and receives data within the NIC

does not check the actual connection pins

T1 (1.544 Mbps)

T3 (45 Mbps)

T1 and T3 connected telephone service to customer

is the device that connects the T1 or T3 to your network

channel service unit/ digital service unit

A CSU/DSU is required on each end of the T1 or T3 line

many new routers have it built-in to them

European counterpart to T1 and T3 are E1 and D3

Carrier Channels Speed

T1 24 1.544 Mbps

T3 672 44.736 Mbps

E1 32 2.048 Mbps

E3 512 34.368 Mbps

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Boding

bond two NICs together as one single connection physically add another NIC card on the computer, then make another cable connection to

the switch

aka Link Aggregation ; NIC Teaming

the Link Aggregation Control Protocol (LACP) controls how multiple network devices

operate as a single connection

802.3 Ethernet Standards **

10BaseT

Cable Type: Cat3 & Cat5

Max Distance: 100 meters Bandwidth: 10 Mbps

100BaseTX

Cable Type: Cat5

Max Distance: 100 meters

Bandwidth: 100 Mbps

100BaseFX

Cable Type: Fiber-Optic


Bandwidth: 100 Mbps

100BaseX

Cable Type: Fiber Optic

Max Distance: 70 km

Bandwidth: 1000 Mbps (1 Gbps)

1000BaseT

Cable Type: Cat5 & Cat5e & Cat6


Bandwidth: 1000 Mbps (1 Gbps)

1000BaseX

{ Wireless }

802.11 Wireless Standards

802.11a

Frequency: 5 GHz

54 Mbps

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Range: 20-45 meters

802.11b

Frequency: 2.4 GHz

11 Mbps

Range: 45 - 120 meters

uses WEP for security

802.11g

Frequency: 2.4 GHz

54 Mbps

Range: 30 -100 meters

compatible with 802.11a and 802.11b

802.11n

Frequency: 2.4 GHz or 5 GHz

600 Mbps

Range: 100 - 200 meters

MIMO - device can use multiple antennas

Compatible with 802.11b and 802.11g

Encryption

WEP (Wired Equivalent Privacy)

64-bit key

WPA (WiFi Protected Access)

128-bit key

WPA 2

256-bit key (best encryption)

Encryption Protocol

TKIP

AES

replaced TKIP

used in WPA2

best encryption

Extra Notes:

Packet Sniffer

used to capture network data

hardware or software device

Port Scanner

mointor traffic coming into and out of ports

Documents

CompTIA Network+ Notes