ccna networking

layer 1

physical (cables, hubs, etc) (uses bits)

layer 2

data link (mac addresses, switches, frames) 

layer 3

network (ip addressing, routers) (uses packets)

layer 4

transport (tcp/udp, ports)(uses segments)

layer 5

session (manages sessions)

layer 6

presentation (encryption, formatting)

layer 7

application (http, dns)

how many bits does IPv4 have?

32 (ex. 192.168.1.1)

how many bits in IPv6?

128 (ex.2001:0db8:85a3:0000:0000:8a2e:0370:7334)

private ip ranges

• 10.0.0.0/8

• 172.16.0.0–172.31.0.0

• 192.168.0.0/16

internet

global network

intranet

internal company network

extranet

third party partners are allowed

what does dhcp do and what port is it?

assigns ip addresses automatically, port 67/68

what does a switch do?

connects multiple devices together so they can communicate

what does a router do?

connects different networks (ex. LAN to WAN)

where would LAN be used

small areas like home, office, or school

where would WAN be used?

large geographic areas like the internet or site to site VPNs

what is a firewall?

security device that filters traffic and blocks ports, IPs or protocols

RDP (remote desktop services) port?

3389

DNS port?

53

SSH port?

22

HTTP port

80

HTTPS port

443

DNS port

53

SNMP port

161

what does DNS do?

resolves domain names into IP addresses

what is tcp (transmission control protocol)

reliable, connection oriented, slow but accurate, and ordered

what is UDP (user datagram protocol)

unreliable, connectionless, fast, unordered

what are straight through cables used for

when you need to connect unlike devices (ex. switch to router)

what are crossover cable used for 

when you need to connect like devices (ex. pc to pc, router to router)

T-568 B order

white orange, orange, white green, blue, white blue, green, white brown, brown

T-568 A order (hint. switch 2 and 6, 1 and 3)

white green, green, white orange, blue, white blue, orange, white brown, brown

if both ends are the same then its…

straight through

if one end is T-586 B another 586 A then its…

crossover

what is rollover cable

has no T586, used only to connect computer to the console port of a switch/router (only for configuration)

bus topology pros and cons

setup: one main cable with devices branching off it

pros: easy to set up, cheap, less cable used
cons: slow, collisions often, main cable failure = whole network down

star topology pros and cons

setup: all devices connect to a central switch/hub
pros: easy to manage, easy to add/remove devices, faster & less collisions, one device failure doesn’t impact others

cons: more cable needed, central device failure = whole network down

ring topology pros and cons

setup: devices connected in a circle, data moves in 1 direction
pros: predictable performance, no collisions
cons: one device failure breaks the network, hard to troubleshoot, slow if many devices

mesh topology pros and cons

setup: devices all connected to each other
pros: reliable, no single point of failure, high performance
cons: expensive, lots of cabling, complicated setup

cat 3 speed

10 mbps

cat 5 speed

100 mhz to 100 mbps

cat 5e speed

1 gbps

cat 6 speed

250 mhz to 10 gbps

cat 6a speed

500 mhz

what is a vpn

secure connection, lets you access a private network over the internet

what does ipconfig /displaydns do

show cached dns records

what does ipconfig /flushdns do

clears dns resolver cache

what does tracert do?

show hops

what does netstat -a do

show all active ports

what does netstat -s do

show network statistics

-t is for?

tcp ports

-a is for

showing all connections/listeners

what metric does RIP use

hop count

port for FTP

20/21

A record?

maps hostname for IPv4 address

AAAA

maps hostname for IPv6 address

802.11a frequency and max speed?

5 ghz
54 mbps

802.11b frequency and max speed?

2.4 ghz
11 mbps

802.11c frequency and max speed?

2.4 ghz
54 mbps

802.11n frequency and max speed?

2.4 & 5 ghz
600 mbps

802.11ac frequency and max speed?

5 ghz
up to 1.3 gpbs

infrastucture mode

wireless devices connect through an access point (like home wifi to a router)

what is ad hoc mode?

devices connect directly to eachother with no access point (like airdropping a picture )

what is peer to peer?

where a device acts as both a client and a server (like sharing files between home PCs without a server)

*TCP MODEL* application layer order and what it does

first, provides network services to apps (http, ftp, etc)

*TCP MODEL* transport layer order and what it does

second, host-to-host communication (tcp, udp)

*TCP MODEL* internet layer order and what it does

third, logical addressing and routing (IP, ARP)

*TCP MODEL* link layer order and what it does

fourth, physical network access and mac addressing (ethernet, wifi)

what OSI models correlate with application

session, presentation, and application