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SSCP > Chapter 3 - Basic Networking and Communications > Flashcards

Chapter 3 - Basic Networking and Communications Flashcards

1
Q

What are the 7 layers of the OSI model?

A

Application
Presentation
Session

Transport
Network
Data Link
Physical

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2
Q

Which layer is responsible for identifying and establishing the availability of communication partners?

A

Layer 7 - Application Layer

Layer 7 provides an interface for information to be sent down the stack.

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3
Q

Which layer is data standardised for transport?

A

Layer 6 - Presentation Layer

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4
Q

Which layer does data compression, decompression, encryption and decryption associated with?

A

Layer 6 - Presentation Layer

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5
Q

Which layer is responsible for setting up and managing sessions between presentation layer entities allowing multiple applications to be open at the same time?

A

Layer 5 - Session Layer

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6
Q

Which layer is responsible for segmentation and reassembly of data?

A

Layer 4 - Transport Layer

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7
Q

Which layer is responsible for TCP/UDP?

A

Layer 4 - Transport Layer

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8
Q

What is Transport Layer Multiplexing and de-Multiplexing?

A

The gathering of chunks of data from different sockets which are then encapsulated with transport layer headers.

Transport layer headers contains information such as source/destination port.

This labelling systems allows data to be sent via a single data stream.

de-Multiplexing reverses this, taking a single data stream and ensures packets are sent to the correct ports.

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9
Q

What is Transport Layer Flow Control?

A

Provides a governance on the amount of data sent by the sender.

Flow control ensures that recipient is not receiving too much data which can overflow its buffer and result in data loss.

Delivered segments are acknowledged back to the sender upon receipt.

Once acknowledgements are received, the sender can continue with sending data.

If the sender acknowledges that it is close to its buffer capacity, it sends a “not ready” indicator to halt data transfer.

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10
Q

What is Transport Layer Windowing?

A

The transport layer windows defines how much data can be sent before needing an acknowledgement.

Sending one packet at a time with a single acknowledgement will be cumbersome.

A defined window size of ‘n’ will allow the sender to send ‘n’ amount of data before needing to receive an “received acknowledgement”

‘n’ could be changed depending on whether speed needs to be increased or slowed down based on the rate of successful delivery.

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11
Q

What is Transport Layer “Positive Acknowledgement with Retransmission”?

A

When a segment is sent to the receiving host, the sender starts a timer and if this time expires prior to the sender receiving an acknowledgement message from the receiver then the data segment is transmitted again.

Absence of acknowledgment message suggests that data was not received.

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12
Q

Which layer manages “local device addressing” tracking the location of each of the device within the network and determining the best way to move data along the network?

A

Layer 3 - Network Layer

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13
Q

What are Layer 3 “Route Information Protocols”?

A

RIP packet are used to update routers about changes to a network such as addition/removal of devices.

RIP packets are used to update routing tables on each router.

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14
Q

Are Network Addresses protocol specific?

A

Yes - Ipv6 and Ipv6 are different addressing schemes and thus routing tables must be maintained dependent on the addressing scheme used.

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15
Q

What are layer 3 ‘Routing Metrics’?

A

Routing metrics are used by routers to determine the best route among different routing routes.

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16
Q

Which layer is responsible for the physical transmission of data, network topology and flow control?

A

Layer 2 - Data Link Layer

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17
Q

Which layer does MAC address operate in?

A

Layer 2 - Data Link Layer

Also adds information such as source and destination MAC address

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18
Q

What does the Logical Link Control (LLC) responsible for?

A

Enables the “Multiplexing” mechanism

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19
Q

What layer does bits send and arrive in the form of electrical signals, light signals etc?

A

Layer 1 - Physical Layer

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20
Q

What are network “backbone” and “segments”

A

Networks are segmented and typically connected to a fast and highly-reliable backbone.

Network segments are any small section of the network which are connected but are not part of the network backbone.

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21
Q

What are network collisions?

A

Network collisions occur when two or more network nodes attempt to send data simultaneously which can result in loss of data during transmission.

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22
Q

What is CSMA/CD relating to collision avoidance?

A

In CSMA/CS network devices can detect when collisions occur and sends out a message to let other devices know that a collision has occurred, each device then waits a random amount of time prior to resending.

CD = Collision Detection

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23
Q

What is the difference between full-duplex and half-duplex wires?

A

Full duplex wires uses two sets of wires - one for sending, one for receiving data.

Half duplex wires has one set of wires which is used for both sending and receiving which allows collisions to occur.

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24
Q

What is CSMA/CA relating to collision avoidance?

A

CSMA/CA listens to the network prior to transmission of data.

If devices are transmitting, they wait a random number of time before listening again for any ongoing transmissions.

CSMA/CA also supports Request to Send (RTS) and Clear to Send (CTS) traffic messages.

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25
Q

What are the 4 steps in DHCP host configuration?

A
  1. DHCP Discovery
    - Client broadcasts a message looking for a DHCP server
  2. DHCP Offer
    - Server offers a client an IP address, subnet mask and IP address of DHCP server making the offer
  3. DHCP Request
    - Client accepts DHCP offered IP address
  4. DHCP Ack
    - DHCP server responds to the client with a ‘DHCP Ack’ message
    - Once received, the client configures itself using the information provided by DHCP server
26
Q

What does ARP message do?

A

ARP resolved IP address to MAC address.

  • The message is essentially “I have this IP address, if you have it tell me your MAC address”

rARP does the reverse.

27
Q

What does NDP message do?

A

Network Discovery Protocol (NDP) - does what ARP does but for IPv6.

ARP = IPv4

NDP = IPv6

28
Q

What port does DNS use?

A

Client > DNS uses UDP 53

DNS > DNS servers TCP 53

29
Q

What port does DHCP use?

A

UDP 67 to send

UDP 68 to receive

30
Q

What is used to validate DNS response to ensure data integrity?

A

DNSSEC

31
Q

What are Internet Control Messaging Protocol (ICMP) packets used for?

A

ICMP packets are used for network diagnostics such as ping, pathping, tracecert etc.

Can be blocked by firewalls due to potential DDos avenues.

32
Q

What are Internet Group Messaging Protocol (IGMP) packets used for?

A

IGMP is used for Ipv4 Multicasting

33
Q

What are Simple Network Management Protocol (SNMP) used for?

A

SNMP is used for managing layer 3 devices.

Nodes running SNMP sends errors and other notifications back to the central SNMP managing software.

SNMP can also be used to configure devices remotely.

SNMP is commonly confined to internal networks.

34
Q

What ports does SNMP use?

A

Receives via UDP 161

Sends via UDP 162

TLS encrypted uses UDP 10161 and UDP 10162

35
Q

What port does FTP use?

A

TCP 20 and TCP 21

FTP supports authentication but data is sent in plaintext

36
Q

What port does TFTP use?

A

TFTP uses UDP 69

Used to transfer small files such as configuration files between network devices

37
Q

What is the difference between SFTP and FTP?

A

SFTP is encrypted using SSH

38
Q

What port does Telnet use?

A

TCP 23

39
Q

What port does SSH use?

A

TCP 22

SSH supports client and server authentication

40
Q

What port does Telnet use?

A

TCP 23

41
Q

What port does SSH use?

A

TCP 22

42
Q

What port does HTTP use?

A

TCP 80

43
Q

What port does HTTPS use?

A

TCP 443

44
Q

What are routing protocols?

A

Routing protocols identify the best path for data to use when traversing through a network.

Routing Information Protocol (RIP)
- Does not scale well as it generated a lot of traffic
- Easy to configure and works well in small networks

Open Shortest Path First (OSPF)
- Scales well in larger networks
- Takes longer to set up than RIP

45
Q

What are the three most popular email protocols?

A

SMTP
POP3
IMAP4

46
Q

What port does SMTP use?

A

Port 25

Port 465 with TLS

47
Q

What port does POP3 use?

A

Port 110

Port 995 with TLS

48
Q

What port does IMAP4 use?

A

Port 143

port 993 with TLS

49
Q

What is IPsec?

A

IPsec secures internet protocol data by providing authentication and encryption.

It provides a way to provide a way to secure data communication over unsecured networks.

IPsec can be used as a tunneling protocol.

50
Q

What is IPsec Authentication Header (AH)?

A

Authentication header is created from the hash of the data packet with additional authentication data.

This hash is encrypted and this provides authentication and integrity.

Protocol 51

51
Q

What is IPsec Encapsulating Security Protocol (ESP)?

A

ESP is similar to AH but is identified using Protocol 50

52
Q

What are Tunneling Protocols?

A

Tunneling Protocols encapsulate data along with encrypting the encapsulated data.

Point-to-Point Tunneling Protocol (PTPP) uses TCP 1723

Layer 2 Tunneling Protocol (L2TP) uses UDP 1701

TLS is an example of a tunneling protocol

53
Q

What is an organization’s Extranet?

A

Network shared between an organization and their trusted 3rd parties.

54
Q

What are Link Local Addresses? (LLA)

A

A small range of IP addresses assigned automatically to clients when clients do not receive an IP address from the DHCP server.

LLA data can only pass within its own subnet - cannot traverse routers.

55
Q

What is Network Address Translation (NAT)?

A

NAT allows a client to access the public internet without the need of an assigned public IP.

For large organizations this will be a proxy server.

For home/small networks the NAT will be the router.

NAT can be assigned static or dynamic

56
Q

What is One-Way trust model?

A

Data is trusted to go one way only.

57
Q

What is a Two-Way trust model?

A

Data is trusted to go both ways bi-directionally.

58
Q

What is Transitive trust model?

A

A <>B

B<>C

Which in turns allow data flow between A <> C but this is not automatic and needs to be authorized.

59
Q

What is a RADIUS server?

A

A RADIUS server provides AAA for clients trying to access a protected source such as a network endpoint.

Endpoints such as Wi-Fi, VPN or applications.

60
Q

What is the preferred method of securing wireless communication?

A

WPA2 with CCMP

61
Q

What are the different types of bluetooth attacks?

A

BlueSnarfing: Unsolicited access to device data through bluetooth

BlueBugging: Unsolicited commands in a device through bluetooth

BlueJacking: Unsolicited messages/notifications through bluetooth

62
Q

What is WiMax?

A

WiMax provides broadband coverage to large/metropolitan areas.

SSCP (14 decks)

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