Chapter 1: Networking Models, Ports, Protocols, and Services

Question 1

OSI reference model

Answer 1

Network architecture that enables data to be passed between computer systems

Question 2

Two common networking models ?

Answer 2

TCP/IP and OSI

Question 3

Mnemonic for OSI layers ?

Answer 3

All people seem to need data processing

Question 4

Physical layer

Answer 4

Defines the physical structure of the network and the topology

Question 5

What makes up the layer 1 hardware ?

Answer 5

Media used on the network, such as type of cable, type of connector, and pinout format for cables

Question 6

Common topolgies today ?

Answer 6

Mesh, star/hub and spoke, spine and leaf, point-to-point, and hybrid

Question 7

Which protocols and technologies operate at layer 1 ?

Answer 7

Ethernet, Bluetooth, ISDN, GSM, DSL, T-carrier links, and USB

Question 8

What other characteristics can the physical layer define ?

Answer 8

The voltage used on a given medium
The frequency at which the signals carrying the data operate

Question 9

What do these additional characteristics dictate ?

Answer 9

Speed and bandwidth of a given medium
Maximum distance over which a certain media type can be used

Question 10

Data Link Layer

Answer 10

Node-to-node delivery of data

Question 11

Frame

Answer 11

Logical grouping of data at layer 2

Question 12

What else does the MAC sublayer control ?

Answer 12

How devices access a shared transmission medium, such as an Ethernet or fiber optic cable

Question 13

What is the LLC sublayer responsible for ?

Answer 13

Error and flow-control mechanisms

Question 14

What protocols and technologies operate at layer 2 ?

Answer 14

High-level data Link control (HDLC)
Layer 2 tunneling protocol (L2TP)
Point-to-point protocol (PPP)
Point-to-point tunneling protocol (PPTP)
Spanning tree protocol (STP)
Virtual LANs (VLANs)

Question 15

Network Layer

Answer 15

Responsible for routing, providing mechanisms by which data can be passed from one network to another.

Question 16

How is functionality provided at the Network Layer?

Answer 16

Routing protocols, which are software components

Question 17

What are protocols responsible for ?

Answer 17

Route selection

Question 18

Packet

Answer 18

Logical grouping of data at the Network Layer

Question 19

Two ways for routes to be configured ?

Answer 19

Static or dynamic

Question 20

Static routes

Answer 20

Manually added to the routing table

Question 21

Dynamic routes

Answer 21

Use routing protocols such as Routing Information Protocol (RIP) and Open Shortest Path First (OSPF)

Question 22

Other important protocols at layer 3 ?

Answer 22

IP, ARP Reverse ARP (RARP), Asynchronous Transfer Mode (ATM), IS-IS, IPSec, ICMP, Multiprotocl label switching (MPLS)

Question 23

Transport layer

Answer 23

Provide mechanisms to transport data between network devices

Question 24

What are three provided mechanisms from layer 4 ?

Answer 24

Error checking, segmentation, and service addressing

Question 25

Error checking

Answer 25

Ensure data is correctly sent or received

Question 26

Service addressing

Answer 26

Ensure data is passed to the right service

Question 27

Segmentation

Answer 27

Break packets into a manageable size

Question 28

What is the transport layer also responsible for ?

Answer 28

Data flow control

Question 29

Data flow control

Answer 29

How the receiving system can receive transmissions

Question 30

Two common methods of flow control ?

Answer 30

Buffering and winnowing

Question 31

Buffering

Answer 31

Data is temporarily stored and waits for the destination device to become available

Question 32

Windowing

Answer 32

Data is sent in a group of segments that require only one acknowledgement

Question 33

Session layer

Answer 33

Responsible for managing and controlling the synchronization of data between applications on two devices

Question 34

How does the session layer handle conversations between applications ?

Answer 34

Establishing, coordinates, or terminates them

Question 35

What are protocols that operate at the session layer ?

Answer 35

NetBIOS, Network file system (NFS), Server message block (SMB)

Question 36

Presentation layer

Answer 36

Convert data intended for or received from the application layer into another usable format

Question 37

Common data formats

Answer 37

Graphic files, text and data, sound/video

Question 38

Graphic files

Answer 38

JPEG, TIFF, GIF

Question 39

Text and data

Answer 39

Data can be translated into different formats such as the American Standard Code for Information Interchange (ASCII) and Extended Binary Coded Decimal Interchange Code (EBCDIC)

Question 40

Sound/video

Answer 40

MPEG, MP3, MIDI

Question 41

Another important function of layer 6 ?

Answer 41

Encryption and decryption

Question 42

What cryptographic protocol operates at layer 6 ?

Answer 42

Transport layer security (TLS)

Question 43

Application layer

Answer 43

Provides access to the network for applications

Question 44

Protocols at layer 7 ?

Answer 44

SSH, BGP, DHCP, DNS, NTP, SMTP, SMB, FTP, HTTP, HTTPS, IMAP, POP3, Real-time transport protocol (RTP), Session initiation protocol (SIP)

Question 45

Connection oriented

Answer 45

Data delivery is guaranteed, with higher overhead and greater bandwidth demand

Question 46

Connectionless

Answer 46

Information is just sent with no mechanism to resend data

Question 47

Internet protocol

Answer 47

Transport data from one node on a network to another

Question 48

What else does IP perform for network transmissions ?

Answer 48

Fragmentation and reassembly tasks

Question 49

What other features does TCP add to IP communications?

Answer 49

Flow control, sequencing, error detection and correction

Question 50

TCP three way handshake

Answer 50

SYN, SYN ACK, ACK

Question 51

Time-outs

Answer 51

Sending host auto retransmit data if receipt is not acknowledged at a given time period

Question 52

UDP header fields?

Answer 52

4

Question 53

Does UDP need to establish a session ?

Answer 53

No

Question 54

Internet control message protocol (ICMP)

Answer 54

Provide error checking and reporting functionality

Question 55

ICMP's most common function ?

Answer 55

Ping utility

Question 56

Ping

Answer 56

Stream of ICMP each requests to a remote host

Question 57

Destination unreachable

Answer 57

Destination can't be contacted

Question 58

Time exceeded

Answer 58

TTL has exceeded

Question 59

Traceroute

Answer 59

Uses IP packets TTL time-outs to discover the path a packet takes

Question 60

ICMP source quench

Answer 60

Tells the sender to slow down. Happens during data influx

Question 61

Internet protocol security (IPSec)

Answer 61

Designed to provide secure communications between systems

Question 62

What two protocols make up IPSec ?

Answer 62

Authentication header (AH) Encapsulating security payload (ESP)

Question 63

Authentication header (AH)

Answer 63

Provided authentication and integrity checking data packets

Question 64

Encapsulating security payload (ESP)

Answer 64

Provides encryption services