Day 2 Flashcards
OSI Model
refer to diagram 6-1 in student workbook
Application Presentation Session Transport Network Data link Physical
Application Layer (layer 7)
The interface between the user’s applications and the network when the user’s network-aware application requires network resources to accomplish a task.
Uses API’s
Presentation Layer (layer 6)
Responsible for presenting the data at the destination with the same meaning and appearance as it had at the source
Session Layer (Layer 5)
Sets up, coordinates, and terminates conversations, exchanges, and dialogues between devices across a network.
Sessions can be:
simplex: communications occur in only one direction
half-duplex: communications occur in two directions but not at the same time
full-duplex: communications occur in two directions simultaneously
transport layer (layer 4)
manages data delivery between systems or hosts
network layer (layer 3)
responsible for the logical addressing and routing of messages to their proper final destination.
data link layer (layer 2)
provides reliable method of transmitting data across the communication link.
Contains two sub layers:
LLC: Upper layer and handles error checking and flow control, and communicates with network layer
MAC: lower layer and is responsible for mapping between logical and physical addressing
physical layer (layer 1)
where communications between devices actually take place
Project 802
IEEE group/standard that defines how multiple computers can connect without interfering with one another
- 3 Ethernet LAN-CSMA/CD
- 5 Token Ring LAN
- 11 Wireless LAN (WLAN) & Mesh (Wi-Fi certification)
Protocols
rules that govern a convention or standard that enables data transfer between two computing endpoints
TCP/IP suite
most common suite in the world
developed by DOD
primarily operates in the client/server model
is routable
network adapter/network interface card
provides interface between a computer and the network medium
link lights
show status of the NIC:
green indicates a good connection
yellow means slow connection speeds
no light indicates a connection is not present
attenuation
the loss of signal intensity over distance
amplifier
a device that strengthens any noise, both intended noise and background noise
repeater
receives and regenerates the original and desired signal
hubs
multipoint repeaters that receive a digital signal, regenerate it, and then broadcast that signal to all connected ports
switches
switches make decisions based on physical MAC addresses and only forward data through the appropriate port
(break up collision domains but not broadcast domains)
routers
connects LAN’s and WAN’s.
determines the next network to which a packet is sent by scanning the destination IP address
uplink port
device that electronically switches the transmit and receive wires eliminating the need for cross over cables.
unicast addressing
sends traffic to a single host or destination
multicast addressing
sends traffic to a group of hosts or recipients
broadcast addressing
used to send traffic to everyone on a LAN
anycast addressing
maps traffic to the nearest host providing a specific service
MAC address
48 bit (6-byte) hex (physical) address burned into the NIC
OUI
first half of the MAC address that identifies the manufacturer
a broadcast to all MAC addresses is FF:FF:FF:FF:FF:FF
IPv4 address
4 octets
8 bits in an octet
0-255 in each octet
subnet masks
identifies where the network part of the IP address stops and the host part begins
Address resolution Protocol (ARP)
used to populate a hosts ARP cache when it knows the IP address of a computer in its network but not any MAC’s. The host sends a message to the IP address it knows and broadcasts it to all MAC’s. All of the hosts update their own ARP cache with the MAC that sent the message, and the intended IP host responds back to the host with its MAC.
Reverse ARP
when a host knows a MAC address but not the IP address.
classes of IP addresses
A 0-127 255.0.0.0 /8
B 128-191 255.255.0.0 /16
C 192-223 255.255.255.0 /24
CIDR
denotes subnet mask and the size of the network
subnetting
breaks larger networks into smaller networks, which contain fewer available host ID’s due to borrowing bits
performing subnetting
refer to info sheet 6-3 in student workbook formula's number of subnets: 2^n n= borrowed bits number of hosts: 2^h-2 h=host bits
Private IP ranges
A 10.0.0.0-10.255.255.255
B 172.16.0.0-172.31.255.255
C 192.168.0.0-192.168.255.255
Automatic Private IP addressing (APIPA)
when a machine cannot reach a DHCP server, it assigns itself its own address so that it can communicate within its own network.
Range:
169.254.0.0-169.254.255.255
loopback address
used to test a NIC’s ability to send or receive traffic
127.0.0.1
ipconfig
displays IP configurations
ifconfig
used in UNIX to display and change parameters such as IP addresses
supernetting
opposite of subnetting, network bits are taken back and utilized as host bits
