OA Test Review Flashcards
OSI Application Layer Function
interacts with end users
OSI Presentation Layer Function
formats the data so it can be viewed by the user
OSI Session Layer Function
establishes and ends connections between 2 hosts
OSI Transport Layer Function
breaks data into packets and transmits them over networks. Flow control and error checking
OSI Network Layer Function
reads the IP address from the packet
OSI Data Link Layer Function
transmits info on computers connected to the same LAN. Reads the MAC address on the packet
OSI Physical Layer Function
translates binary into the language of the transport medium
TCPIP Application layer function
interacts with apps that need to gain access to network services
TCPIP host to host/transport layer function
segments data and validates it hasn’t been corrupted
TCPIP network/internet layer function
routing of packets as they move around the network
TCPIP physical layer function
protocols interface with medium
Layer Devices
7. application
6. presentation
5. session
4. transport
3. network
2.data link
1. physical
- gateway, firewall, endpoint device
- gateway, firewall, server, PC
- gateway, firewall, server, PC
- gateway, firewall
- router, brouter, layer 3 switch
- bridge modem, network card, layer 2 switch
- hub, repeater, cable, fiber, wireless
TCPIP Layer Protocols
4. application
3. host to host/transport
2. network/internet
1. physical
- telnet, smtp, ftp, http
- TCP, UDP
- IP, ICMP, ARP, DHCP
- ethernet, PPP, ADSL
TCPIP Application Layer Function
interacts with apps that need to gain access to network services
TCPIP Host to Host/transport Layer Function
segments data and validates it hasn’t been corrupted
TCPIP Network or internet layer function
routing of packets as they move around the network
Physical or Network access layer function
high layer protocols interface with transport mediums
Attenuation
signal loss on transmission media
hub
hardware device with ports for multiple connections that echoes every message it receives to ALL connected ports
switch
device with multiple ports but examines the message and knows which port it should forward the message to. allows multiple devices to communicate
host based network
central computer/main frame with many users that connect directly to it using terminals such as keyboard and monitor
client server internetworking
central server handles data and local client software on client devices that requests services from server
peer to peer internetworking
use of an enterprise network for peers to exchange messages without depending on a central server to manage connections and messages
bridge
device needed for internetworking at the data link layer. listens to received traffic and remembers ports on which the traffic arrived from each MAC address. interconnects 2 or more LANs
router
forward IP packets based on where that IP network is physically located and the physical port or interface that connects to it
NIC network interface controller
allows device to connect and communicate on the network
prevention broadcast stormed caused by loops
uses RSTP or MSTP to stop packets from traveling in a circle and never reaching a destination
VLAN
used in flat topology where there is no hierarchy to the network structure.
circuit switched
a network that creates a path between a source and destination device
extranet
private network that allows authorized external users to securely share info
internet protocol IP
part of TCPIP that makes it possible to deliver packets across complicated networks by handling routing decisions
internetworking
the process of connecting multiple computer networks
intranet
private internal network
logical topology
shows how the devices in a network connect to a specific segment of the network
OSI Reference Model
internationally accepted framework of standards that governs how separate computer systems communicate using networks
packet switched
networks that transmit packets as individual messages
physical topology
physical network devices and any physical devices used to connect to the network
point to point network
network that consists only of computers and devices that are connected directly
TCP
part of the TCPIP that guarantees a reliable stream of data between two computers
TCPIP Reference Model
descriptive framework for computer network protocols created by DoD in the 70s
TCPIP Suite
a collection that provides support to nearly all internet capable operation systems and devices
TCPIP Data Link sublayer- logical link layer LLC
top layer that talks directly to the network layer and provides error control
TCPIP Data link sublayer- media access control layer
talks to the physical layer and defines how frames are placed on the wire
well known ports
0-1023
registered ports
1024-49151
dynamic ports
49151-65535
3 way handshake
syn (synchronize), syn/ack, ack (acknowledge)
bit
binary digit
nibble
collection of 4 bits (half a byte or half an octet)
byte
number of bits a system has used to encode one text character. 8 bits.
IPv4 IP address length
32 bits= 4 bytes= 4 octets
IPv6 IP address length
8 groups of 4 hexdigits, each group of 4 hexdigits= 16 bits, so 128 bits
IPv6 IP address set up
first 48 bits=network
next 16 bits=subnet ID
last 64 bits= client ID
T568A wire
starts with green, residential
T568B wire
starts with orange, commercial
Class A address Subnet Mast
255.0.0.0
Class B address subnet mask
255.255.0.0
class c address subnet mask
255.255.255.0
reliability
availability and integrity of the data transmission
uptime
whether there is a physical link access to the communication line
integrity
whether the data made it to the destination intact and accurate
6 components of a structured wiring system
- building cabling entrance
- data center/equipment room
- backbone cabling
- telecom room/wiring closet
- horizontal cabling
- workstation/office location
attenuation
measure amount of signal loss at the other end
crosstalk
where a signal on one pair of twisted cables interferes with another pair
propagation delay
amount of time it takes for signal to reach the end of the cable
return loss
measures signal reflections that are caused by an impedance mismatch from end to end
802.3
ethernet standards
CSMA/CD carrier sense
NIC cards listen on the physical media for specific voltage levels or carrier signals. if coast is clear, NIC can transmit
CSMA/CD multiple access
NIC cards can transmit simultaneously. when this happens, a collision is noticed by the NIC card transceivers
CSMA/CD collision detection
NIC cards react to signal collisions by retransmitting after receiving a notification that a collision occurred
Multilayer hierarchal backbone
each departmental LAN connects to a common chassis based high speed backbone. traffic bound for other departments and workgroups, must be sent to the department’s router
flat backbone
each departmental LAN connects to a common chassis based high speed backbone. traffic bound for departmental LANs is layer 2 switched via VLANs and ethernet tagging to direct traffic between departmental LAN locations
collapsed backbone
aka backbone in a box or inverted backbone.
data link layer- aka
protocol layer
ethernet
wired system for connecting devices in a LAN, MAN, and WAN
protocol
established set of rules to determine how data can be transmitted across devices
redundancy
process of providing alternate means for a network to continue functioning
repeater
device that receives and amplifies a signal
resilience
ability to continue providing acceptable service despite operations challenges
protocols operating at network layer/layer 3
IP, ICMP, IPSec, appletalk
protocols operating at transport layer/layer 4
TCP and UDP
tranport layer/layer 4 services provided
flow control
fragmentation and reassembly
error control
acknowledgement of delivery
addressing
identifies source and destination host
IPv6 provides the following services
version
traffic class
flow label
addressing
how application layer refers to data
APDU: application protocol data unit
how presentation layer refers to data
PPDU: presentation protocol data unit
how session layer refers to data
SPDU: session protocol data unit
how transport layer refers to data
segment or datagram
how network layer refers to data
packet
how data link layer refers to data
frame
how physical layer refers to data
bits
MAC address
hardware address on TCPIP host that never changes
MAC address length
48 bits
MAC address set up
first half is OUI
second half is vendor assigned
IPv4 loopback address
127.0.0.1
SLAAC
stateless address autoconfig
autogenerates a link local address
loopback address starts with ::1
unicast network methodology
sending a packet to a single destination
anycast network methodology
sending a packet to the nearest node in a specified group of nodes
multicast network methodology
sending a packet to multiple destination
types of connectionless communication
UDP, ICMP, DNS, TFTP, SNMP
connection oriented protocol
sets up a connection between the source and destination
connectionless protocol
treats each connection individually
datagram
packets that are transmitted across networks
IANA
oversees all allocations of IP addresses
NAT
maps local private addresses to public ones
full duplex mode of communication
both ends of communication communicate simultaneously
half duplex mode of communication
both ends can communicate but 1 at a time
simplex mode of communication
source only sends data to a destination and destination cannot respond
common layer 5 (session layer) protocols
H.254
L2TP
NetBIOS
RPC
SMB
SOCKS
common layer 6 (presentation layer) protocols
IMAP
SSH
SSL
TSL
common file formats for layer 6/presentation
JPEG, GIF, TIFF, MPEG, MIDI
application layer software steps
- accepts some messages as input from application software and adds any additional data such as address of target computer
- calls other software from the next lower layer and sends a new messages (original + new data)
- may chop the message into smaller chunks before sending each chunk to the next layer
- then may wait for a reply
common protocols at layer 7/application
DHCP
HTTP
FTP
RTP
SIP
telnet
SMTP
SNMP
FTP port
20/21
SSH and SFTP port
22
telnet port
23
smtp port
25
DNS port
53
DHCP port
67/68
http port
80
HTTPS port
443
host based application
everything runs off the central host with dumb terminal devices
client based application
data storage function stayed on central server but everything else on client BAD IDEA
client server application
computing split the data and processing tasks into 2 main partitions- server handles data while clients handle the processing
cloud computing/n-tier application
appserver is a program that runs on a central server that handles processing logic. appserver is colocated with database server. once it finished processing, it only sends results over the network to the client
peer to peer applications
peers share data and processing with each other.
malware examples
trojan horse
spyware
virus
worm
ransomware
DoS attack
DDoS
botnets
arpanet
a computer network developed by the DoD to support academic research
layer 2 tunneling protocol
protocol that supports VPNs
web browser
protocol to allow all resources to be linked together
class A private IP addresses
10.0.0.0- 10.255.255.255
class b private IP address
172.16.0.0- 172.31.255.255
class c private IP address
192.168.0.0- 192.168.255.255
internetwork with a gateway
connects networks that use different protocols by translating packets to protocol compatible with destination
lowest cost of connectivity
high port density
first packet switched network
arpanet
broadcast MAC address
ff:ff:ff:ff:ff:ff
patch panel
keeps a large number of cables organized. connect patch cable from workstation to panel to layer 2/layer 3 switch
ICMP
core protocol on IP suite. provides easy method to send short messages. most commonly used for error messages
UDP
best effort, but no guarantee. treats each packet individually
IDS
intrusion detection system. passive, only alerts
IPS
intrusion prevention system. takes action to decide whether to accept or reject packets based on rules
vampire tap
bites into thicknet to connect individual machines to ethernet
media converter
allows you to integrate new equipment into existing cabling infrastructure
most common topology in early ethernet
bus
real time apps benefit from _______
layer 2 switch
router runs on which layer
network layer
which class has the fewest nodes in each network
class c
/24 subnet mask is how many bits
8 bits
NDP: IPv6 as ____: IPv4
ARP
technical safeguards
VLAN segmentation, workstation hardening, redundant network connections
network with lowest TCO
IP based
basic topology for FDDI
ring
what devices supplies PoE
layer 3 switch
access control list
rules governing stateless firewalls to control flow of traffic
what layer does IPSec work
layer 3
port listening on a server set up to automatically assign IP addresses
UDP 67
usability
ability of different parts of network to work together
insecure ports
20, 21, 23, 80
ethernet collision domain
special area created by each port on full duplex layer 2 switch
flood guard
security feature on some switches that blocks some unwanted broadcast messages
number of individual usable VLANs allowed by VLAN field
4094
convergence
all routers are synchronized
IEEE standards for token ring
802.5
Cut through switching
Forwards as soon as it reads the destination address
aggregation of edge networks is a
collapsed backbone
edge network
desktop workstation LAN connection
architecture in which all processing functions are on the client
P2P
kerberos port
88
BGP port
179
SaaS
software applications hosted by vendor. often used through web browser
PaaS
cloud provides an environment for client to build and use their own software
IaaS
cloud provides network access to traditional computing resources such as processing power and storage.
