OSI and TCP/IP Models

Question 1

What are the OSI Layers

Answer 1

Physical
Data Link
Network
Transport
Session
Presentation
Application

Question 2

What happens at the physical layer

Answer 2

Converts a frame into bits for transmission/receiving over the physical connection medium.
Network hardware devices that function at layer 1 include NICs, hubs, repeaters, concentrators, amplifiers.

Question 3

What are physical layer protocol data unit (PDU)

Answer 3

Bits

Question 4

What are common physical layer protocols

Answer 4

Electrical signal (copper wire)
Light Signal (optical fibre)
Radio Signal (air)

Question 5

What are some physical network topologies

Answer 5

Ring
Bus
Star
Mesh

Question 6

What are physical layer attack vectors

Answer 6

Passive sniffing
Excessive Electrical Interference
Cutting a cable

Question 7

What happens at the Data Link Layer

Answer 7

Responsible for formatting a packet for transmission
Adds the source and destination hardware address to the frame
Address Resolution Protocol (ARP) operates at layer 2
Switches and Bridges function at this layer

Question 8

What sublayers of Data Link Layer

Answer 8

Logical Link Control (LLC)
Media Access Control (MAC)

Question 9

What does the Logical Link Control do?

Answer 9

Controls packet synchronization, flow control, and error checking

Question 10

What does the Media Access Control do?

Answer 10

It controls how devices on a network gain permission to transmit data.

Question 11

What are common Data Link Layer protocols

Answer 11

MAC, ARP, Ethernet 802.3 (Wired)
LLDP, HDLC, PPP, DSL, IEEE 802.11(Wireless), SONET/SDH, VLANs

Question 12

What are Data Link Attack Vectors

Answer 12

Address Resolution Protocol spoofing
Man in the Middle Attack
Session Hijacking

Question 13

What happens at the Network Layer

Answer 13

Responsible for logical addressing Providing routing or delivery guidance (not necessarily verifying guaranteed delivery)
Manages error detection and traffic control

Question 14

What are common Network Layers protocols

Answer 14

IPv4
IPv6
IPSec
OSPF
EIGRP
ICMP
RIP
NAT

Question 15

What are Network Layer Attack Vectors

Answer 15

Man in the Middle Attack
Denial of Service
Spoofing IP address

Question 16

What happens at the Transport Layer

Answer 16

Responsible for managing the integrity of a connection and controlling the session. Providing transparent data transport and end to end transmission control
Defines session rules like how much data each segment can contain, how to verify message integrity, and how to determine whether data has been lost
Segmentation, sequencing, and error checking happen on this layer

Question 17

What are common Transport layer protocols

Answer 17

TCP
UDP
SSL
TLS

Question 18

What are Transport layer attack vectors

Answer 18

SYN Flood Attack
Trojans and other malware tend to target specific TCP and UDP ports
Session Hijacking

Question 19

What happens at the Session Layer

Answer 19

Responsible for establishing, maintaining, and terminating communication sessions between two computers
Uses data streams

Question 20

What are the 3 communications session phases

Answer 20

Connection establishment
Data Transfer
Connection release

Question 21

What are common Session layer implemenations

Answer 21

RPC
NFS
SMB
NetBIOS

Question 22

What are Session Layer attack vectors

Answer 22

Protocols such as NFS and NetBIOS may be vulnerable to DoS and root privilege attacks

Question 23

What happens at the Presentation Layer

Answer 23

Responsible for transforming data into format that any system following the OSI model can understand
Uses data streams

Question 24

What are Presentation Layer tasks

Answer 24

data representation
character conversion
data compression
data encryption

Question 25

What are common Presentation layer implementations

Answer 25

Encryption protocols and Format types like ASCII EBCDICM TIFF JPEG, MPEG MIDI

Question 26

What are Presentation Layer Attack Vectors

Answer 26

Crytanalytic Attacks such as Brute Force Ciphertext Only Know Plaintext Frequency Analysis

Question 27

What happens at the Application Layer

Answer 27

Interfacing user applications, network services, or the Operating system with protocol stack Identifying and establishing availabilty of communication partners Determining resources availability Synchronizing communication Uses data streams

Question 28

What are common Application Layer implementations

Answer 28

HTTP FTP LDAP Telnet

Question 29

What are the TCP/IP Layers

Answer 29

Link Layer (Physical and Data Link) Internet Layer (Network) Transport Layer (Transport) Application Layer (Session, Presentation, and Application)

Question 30

What is the Protocol Data Unit (PDU) at the Data Link Layer

Answer 30

Frames

Question 31

Routing Protocols

Answer 31

Move routed protocol messages across a network. Defined at the Network Layer and specify how routers communicate Can be static or dynamic and categorized as interior or exterior Include Internetwork Packet Exchange (IPX) and Internet Protocol (IP)

Question 32

Static Routing Protocol

Answer 32

Requires an admin to create/update routes on the router

Question 33

Dynamic Routing Protocol

Answer 33

Can discover routers and determine best route to a given destination Routing table is periodically updated

Question 34

Distance Vector Router Protocol

Answer 34

An interior router protocol that makes routing decisions based on distance (hop count), and vector (router egress interface)

Question 35

Examples of Distance Vector routing protocol

Answer 35

Routing Information Protocol (RIP): uses hop count as it routing metric Interior Gateway Routing Protocol (IGRP) Enhanced Interior Gateway Routing Protocol (EIGRP)

Question 36

Link State Routing Protocol

Answer 36

An interior routing protocol that uses router characteristics(e.g. speed, latency, error rates) to make next hop routing decisions

Question 37

Examples of Link State routing protocols

Answer 37

Open Shortest Path First(OSPF) an interior gateway routing protocol developed for IP networks based on shortest path first or link state algorithm. Intermediate System to Intermediate System (IS-IS)

Question 38

Interior Routing Protocol

Answer 38

As called "myopic" make next hop decisions based only on info related to the next immediate hop

Question 39

Exterior Router Protocols

Answer 39

As called "far-sighted" makes hop decisions based on the entire remaining path (i.e.) vector

Question 40

Border Gateway Protocol (BGP)

Answer 40

an exterior/path vector protocol

Question 41

Transmission Control Protocol (TCP)

Answer 41

Major transport protocol in the internet suite of protocols. Provides reliable, connection oriented, full duplex streams. Use 3 way handshake: Synchronize (SYN), synchronize-acknowledge (SYN-ACK), and acknowledge(ACK)

Question 42

User Datagram Protocol (UDP)

Answer 42

Connectionless protocol that provides fast, best effort delivery of datagrams(self-container unit of data)

Question 43

What is the Protocol Data Unit (PDU) at the Transport Layer

Answer 43

Segments

Question 44

What is the Protocol Data Unit (PDU) at the Network Layer

Answer 44

Packets

Question 45

Simplex

Answer 45

A one way connection establishment in the session layer

Question 46

Half Duplex

Answer 46

A connection establishment in the session layer where both communication devices can transmit/receive but not at the same time

Question 47

Full Duplex

Answer 47

A connection establishment in the session layer where both communication devices can transmit/receive at the same time

Question 48

What is the Protocol Data Unit (PDU) at the Session Layer

Answer 48

Data

Question 49

What is the Protocol Data Unit (PDU) at the Session Layer

Answer 49

Data

Question 50

What is the Protocol Data Unit (PDU) at the Application Layer

Answer 50

Data