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02 - The role of the four layers (ATNL)

 1. In order for a network like the internet to work, protocols need to be in place. A lot of them! Fill in the blanks
To better understand the various protocols and how they work 
with each other, we use a_____________________
A ______________ shows how the protocols work at each layer 
as well as how the layers interact with the layers either 
above them or below them.

  an internet service provider

  single or simple protocol

  filtered network

  layered model

 2. The layered models that are used in modern computer networks are two; the OSI model (Open Systems Interconnection) and the TCP/IP model (Transmission Control Protocol/ Internet Protocol)

  TRUE

  FALSE

 3. Various 'models' have been developed to help people think about how protocols are organised. Fill in the blanks
These models ______________________ called 'layers' according to their role in  network communications. 

  split the protocols into different groups

  split the cables required into different categories

  split the protocols into different IP addresses

  split the hardware and software required into different groups or keys

 4. So, what really is a 'layer'? (remember it is not an actual thing it is a conceptual model)

  A layer is a cable. Several layers are several cables

  A layer is a TCP/IP protocol that is embedded in the cable itself

  A layer is a group of protocols arranged by function

  A layer is a group of IP addresses arranged by DNS server

 5. In the four layer model (TCP/IP) as with other models, protocols in one layer can only interact with layers directly above and below them.

  TRUE

  FALSE

 6. Why do we use layers?

  All of these mentioned options are valid answers

  Because it can be difficult to conceptualise a complex system like network communication (it has many parts)

  Because it is useful for manufacturers when they are making new hardware/software to ensure it is compatible with all protocols

  So that we can map how protocols relate and interact with each other. (a new protocol can be slotted in to the right layer)

 7. Examine the following list. Which one of the following in the list is NOT a valid protocol.
TCP/IP
UDP
FTP
POP
IMAP
SMTP
Ethernet
X.25
Telnet
TLS
NTP
NNTP

  UDP and FTP are not protcools

  Ethernet and IMAP are not protocols

  They are all valid protocols and there are many more

  Only TCP/IP and SMTP are protocols and there are no others

 8. In the four layer model the Network (Data link) layer is always no. ____________________ at at the ______________.

  There is no such layer called the 'Network' or Data Link layer

  2 / top

  1 / bottom

  4 / top

 9. The fourth layer, usually depicted at the top, is called the ________________ layer.
Note: Each layer has a function to perform

  internet or IP

  Network or Data Link

  application

  transport

 10. This layer holds protocols that governs how data moves in an out of applications (like web browsers, email applications and servers).

  Network or Data Link

  transport

  application

  internet or IP

 11. The _______________ can only interact with the transport layer because it is directly above it.

  Network or Data Link

  application

  transport

  internet or IP

 12. This layer contains protocols or rules that govern the transport of data packets across a network.

  transport

  application

  internet or IP

  Network or Data Link

 13. The _________ part of the TCP/IP internet protocol is an example of a protocol in the transport layer.

  IP

  FTP

  TCP

  DTP

 14. The transport layer provides services for both ___________ mode and ________________ transmissions.

  caught / uncaught

  connection / connectionless

  cabled / non-cabled

  physical / non-physical

 15. Connection mode is when the transmitter just sends packets of data without actually setting up a session (unlike a telephone call)

  TRUE

  FALSE

 16. This layer is responsible for checking for errors.

  Network or Data Link

  application

  transport

  internet or IP

 17. This layer contains protocols that govern how messages are prepared before they are sent and how they are unpacked after they are received.

  application

  transport

  internet or IP

  Network or Data Link

 18. This layer is responsible for handling the physical connection to the network. For example 'Ethernet' is partly a physical protocol so is included here.

  application

  transport

  Network or Data Link

  internet or IP

 19. The functions of the network or data link layer include:

  to deal with tranmission errors

  to regulate the flow of data off and on the physical medium

  All of these mentioned options are valid answers

  to provide an interface between the physical medium and layer 2

 20. What layer do the following protocols belong in?
IP (Internet Protocol)

  application

  Network or Data Link

  transport

  internet or IP

 21. What layer do the following protocols belong in?
FTP, HTTP, POP, IMAP, SMTP

  internet or IP

  Network or Data Link

  application

  transport

 22. What layer do the following protocols belong in?
TCP 

  transport

  internet or IP

  application

  Network or Data Link

 23. What layer do the following protocols belong in?
ETHERNET, WI-FI

  Network or Data Link

  internet or IP

  transport

  application

 24. Communication protocols can be categorised by which layer they fit into within the four layer model.

  FALSE

  TRUE

 25. There are two ways of categorising protocols: _____________ or ________ protocols.

  domain / IP

  application / logical

  Net / internet

  physical / logical

 26. A ________ protocol has a hardware aspect to it, meaning that it defines what hardware is needed to support it.

  None of the above

  logical

  physical

  domainical

 27. The _____________ protocol includes definitions of the performance required of cables, plugs and sockets. E.g 100m is the max length of an Ethernet Cat-5 cable before a repeater is needed.

  ethernet

  physical

  transport

  internet

 28. Logical protocols are not concerned with anything physical - they define the structure,format and control of data entities.

  FALSE

  TRUE

 29. In the four layer model, logical protocols exist in layers ______________

  2 and 4 only

  2,3,4

  1 only

  2 and 3

 30. On reading the following excerpt, can you fill in the blanks?
1. How to set up a connection
2. How to end a connection
3. How to start a message
4. How to end a message
5. How to deal with corrupted data
6. How to format the data being sent

With these rules in place, hardware and software
creators can be sure that _______________________
______________ on a network using that protocol. 

  their devices will show error messages when appropriate

  their devices will work correctly

  None of the above

  their devices will be unique and only operate independently of each other