Lesson 2 - OSI

Question 1

OSI

Answer 1

Open Systems Interconnection

Question 2

The physical layer

Answer 2

Layer 1

Question 3

The data link layer

Answer 3

Layer 2

Question 4

The network layer

Answer 4

Layer 3

Question 5

The transport layer

Answer 5

Layer 4

Question 6

The session layer

Answer 6

Layer 5

Question 7

The presentation layer

Answer 7

Layer 6

Question 8

The application layer

Answer 8

Layer 7

Question 9

At the ______ layer, binary expressions (that is, a series of 1s and 0s) represent data

Answer 9

Physical Layer/Layer 1

Question 10

At upper layers, however, bits are grouped together, into what is known as a ________ or a __________

Answer 10

Protocol Data Unit (PDU) or Data Service Unit

Question 11

Physical layer PDU

Answer 11

Bits

Question 12

Data link layer PDU

Answer 12

Frames

Question 13

Network layer PDU

Answer 13

Packets

Question 14

Transport layer PDU

Answer 14

Segments

Question 15

The concern of the__________ is the transmission of bits on the network along with the physical and electrical characteristics of the network

Answer 15

Physical Layer / Layer 1

Question 16

represents a binary 1 with the presence of voltage (on a copper cable) or the presence of light (on a fiber-optic cable). Similarly, the absence of light or voltage represents a binary 0

Answer 16

Current state modulation

Question 17

One way to electrically or optically represent a binary 1 or 0 is to use the transition between a voltage level (for example, going from a state of no voltage to a state of voltage, or vice versa, on a copper cable) or the transition of having light or no light on a fiber-optic cable to represent a binary 1. Similarly, a binary 0 is represented by having no transition in a voltage level or light level from one time period to the next. This approach of representing binary digits is called ________________

Answer 17

state transition modulation

Question 18

The ___________ layer is concerned with the following:
Packaging data into frames and transmitting those frames on the network
Performing error detection/correction
Uniquely finding network devices with an address
Handling flow control

Answer 18

Data Link Layer / Layer 2

Question 19

The _____________ is primarily concerned with forwarding data based on logical addresses

Answer 19

Network Layer / Layer 3

Question 20

The _________ acts as a dividing line between the upper layers and lower layers of the OSI model. Specifically, messages are taken from upper layers and are encapsulated into segments for transmission to the lower layers.

Answer 20

Transport Layer / Layer 4

Question 21

The _________ is responsible for setting up, maintaining, and tearing down sessions. You can think of a session as a conversation that needs to be treated separately from other sessions to avoid the intermingling of data from different conversations.

Answer 21

Session Layer / Layer 5

Question 22

The __________ handles formatting the data being exchanged and securing that data with encryption.

Answer 22

Presentation Layer / Layer 6

Question 23

The _______ gives services to a network.

Answer 23

Application Layer / Layer 7

Question 24

Network Interfave || Internet || Transport || Application

Answer 24

TCP/IP Stack

Question 25

___________ field. The value in this field is decremented by 1 every time this packet is routed from one IP network to another (that is, passes through a router). If the ____ value ever reaches 0, the packet is discarded from the network.

Answer 25

Time-to-Live (TTL)

Question 26

Due to the sequencing and acknowledgements, ___ is considered to be a connection-oriented transport layer protocol

Answer 26

TCP

Question 27

Dynamically assigns IP address information (for example, IP address, subnet mask, DNS server's IP address, and default gateway's IP address) to a network device

Answer 27

DHCP Dynamic Host Configuration Protocol

Question 28

UDP Port 67, 68

Answer 28

DHCP Dynamic Host Configuration Protocol

Question 29

Resolves domain names to corresponding IP addresses

Answer 29

DNS Domain Name System

Question 30

TCP Port 53 UDP Port 53

Answer 30

DNS Domain Name System

Question 31

Transfers files with a remote host (typically requires authentication of user credentials)

Answer 31

FTP File Transfer Protocol

Question 32

TCP Port 20, 21

Answer 32

FTP File Transfer Protocol

Question 33

A signaling protocol that provides multimedia communications over a network

Answer 33

H.323

Question 34

TCP Port 1720

Answer 34

H.323

Question 35

Retrieves content from a web server

Answer 35

HTTP Hypertext Transfer Protocol

Question 36

TCP Port 80

Answer 36

HTTP Hypertext Transfer Protocol

Question 37

Used to securely retrieve content from a web server

Answer 37

HTTPS Hypertext Transfer Protocol Secure

Question 38

TCP Port 443

Answer 38

HTTPS Hypertext Transfer Protocol Secure

Question 39

Retrieves email from an email server on port 143

Answer 39

IMAP/IMAP4 Internet Message Access Protocol

Question 40

TCP Port 143

Answer 40

IMAP/IMAP4 Internet Message Access Protocol

Question 41

Provides directory services (for example, a user directory that includes username, password, email, and phone number information) to network clients

Answer 41

LDAP: Lightweight Directory Access Protocol

Question 42

TCP Port 389

Answer 42

LDAP: Lightweight Directory Access Protocol

Question 43

A secured version of LDAP

Answer 43

LDAPS Lightweight Directory Access Protocol over SSH

Question 44

TCP Port 636

Answer 44

LDAPS Lightweight Directory Access Protocol over SSH

Question 45

Used as a call control and communication protocol for Voice over IP networks

Answer 45

MGCP Media Gateway Control Protocol

Question 46

UDP Port 2427, 2727

Answer 46

MGCP Media Gateway Control Protocol

Question 47

Provides network communication services for LANs that use NetBIOS

Answer 47

NetBIOS Network Basic Input/Output System

Question 48

TCP Port 139 UDP Port 137, 138

Answer 48

NetBIOS Network Basic Input/Output System

Question 49

Supports the posting and reading of articles on Usenet news servers

Answer 49

NNTP Network News Transport Protocol

Question 50

TCP Port 119

Answer 50

NNTP Network News Transport Protocol

Question 51

Used by a network device to synchronize its clock with a time server

Answer 51

NTP Network Time Protocol

Question 52

UDP Port 123

Answer 52

NTP Network Time Protocol and SNTP Simple Network Time Protocol

Question 53

Retrieves email from an email server port 110

Answer 53

POP3 Post Office Protocol Version 3

Question 54

TCP Port 110

Answer 54

POP3 Post Office Protocol Version 3

Question 55

A Microsoft protocol that allows a user to view and control the desktop of a remote computer

Answer 55

RDP Remote Desktop Protocol

Question 56

TCP Port 3389

Answer 56

RDP Remote Desktop Protocol

Question 57

Allows commands to be executed on a computer from a remote user

Answer 57

rsh Remote Shell

Question 58

Port 514

Answer 58

rsh Remote Shell

Question 59

Used for delivering media-based data (such as Voice over IP) through the network

Answer 59

RTP Real-time Transport Protocol

Question 60

TCP/UDP Ports 5004, 5005

Answer 60

RTP Real-time Transport Protocol

Question 61

Communicates with a media server (for example, a video server) and controls the playback of the server's media files

Answer 61

RTSP Real-Time Streaming Protocol

Question 62

TCP/UDP Port 554

Answer 62

RTSP Real-Time Streaming Protocol

Question 63

Provides a secure file-transfer service over an SSH connection and offers a file's original date and time information, which is not available with FTP. Uses TCP port 22

Answer 63

SCP Secure Copy

Question 64

Provides FTP file-transfer service over an SSH connection. Uses TCP port 22

Answer 64

SFTP

Question 65

Used to create and end sessions for one or more media connections, including Voice over IP calls

Answer 65

SIP Session Initiation Protocol

Question 66

TCP Port 5061 UDP Port 5060

Answer 66

SIP Session Initiation Protocol

Question 67

Used to share files, printers, and other network resources

Answer 67

SMB Server Message Block

Question 68

TCP Port 445

Answer 68

SMB Server Message Block

Question 69

Used for sending email

Answer 69

SMTP Simple Mail Transfer Protocol

Question 70

TCP Port 25

Answer 70

SMTP Simple Mail Transfer Protocol

Question 71

Used to monitor and manage network devices

Answer 71

SNMP Simple Network Management Protocol

Question 72

UDP Port 161

Answer 72

SNMP Simple Network Management Protocol

Question 73

A notification sent from an SNMP agent to an SNMP manager

Answer 73

SNMP Trap Simple Network Management Protocol Trap

Question 74

TCP/UDP 162

Answer 74

SNMP Trap Simple Network Management Protocol Trap

Question 75

Supports time synchronization among network devices, similar to Network Time Protocol

Answer 75

SNTP Simple Network Time Protocol

Question 76

Used to securely connect to a remote host (typically via a terminal emulator)

Answer 76

SSH Secure Shell

Question 77

TCP Port 22

Answer 77

SSH Secure Shell

Question 78

Used to connect to a remote host (typically via a terminal emulator)

Answer 78

Telnet

Question 79

TCP Port 23

Answer 79

Telnet

Question 80

Transfers files with a remote host (does not require authentication of user credentials)

Answer 80

TFTP Trivial File Transfer Protocol

Question 81

UDP Port 69

Answer 81

TFTP Trivial File Transfer Protocol

Question 82

A mathematical algorithm that is executed on a data string by both the sender and the receiver of the data string. If the calculated ___ values match, the receiver can conclude that the data string was not corrupted during transmission.

Answer 82

cyclic redundancy check (CRC)

Question 83

layer of the TCP/IP stack encompasses the technologies addressed by Layers 1 and 2 (that is, the physical and data link layers) of the OSI model.

Answer 83

network interface layer

Question 84

This layer of the TCP/IP stack maps to Layer 3 (network layer) of the OSI model. Although multiple routed protocols (for example, IPv4 and IPv6) may reside at the OSI model's network layer, the ______ layer of the TCP/IP stack focuses on IP as the protocol to be routed through a network.

Answer 84

Internet layer

Question 85

layer of the TCP/IP stack maps to Layer 4 (transport layer) of the OSI model. The two primary protocols found at the TCP/IP stack's transport layer are TCP and UDP.

Answer 85

transport layer (TCP/IP stack)

Question 86

TCP/IP layer that addresses concepts described by Layers 5, 6, and 7 (that is, the session, presentation, and application layers) of the OSI model.

Answer 86

application layer (TCP/IP stack)

Question 87

Supports different communication sessions (for example, different telephone conversations in a telephony network) on the same physical medium by allowing sessions to take turns. For a brief period of time, defined as a time slot, data from the first session is sent, followed by data from the second session. This continues until all sessions have had a turn, and the process repeats itself.

Answer 87

time-division multiplexing (TDM)

Question 88

A connection-oriented transport protocol. Connection-oriented transport protocols provide reliable transport, in that if a segment is dropped, the sender can detect that drop and retransmit that dropped segment. Specifically, a receiver acknowledges segments that it receives. Based on those acknowledgments, a sender can determine which segments were successfully received

Answer 88

Transmission Control Protocol (TCP)

Question 89

A connectionless transport protocol. Connectionless transport protocols provide unreliable transport, in that if a segment is dropped, the sender is unaware of the drop, and no retransmission occurs.

Answer 89

User Datagram Protocol (UDP)

Question 90

Also known as the DoD model, this four-layer model (as opposed to the seven-layer OSI model) targets the suite of TCP/IP protocols.

Answer 90

TCP/IP stack