CS6250 COMPUTER NETWORK EXAM 1 2026/2027
Questions and answers | Correct answers highlighted in green
1.
What are advantages and disadvantages of a layered architecture?
Each protocol
layer offers different services.
2.
Layered Architecture
Each protocol layer offers different services.
3.
Layered Architecture Advantages
- Scalability,
- Flexibility
- Ease of adding / removing components making it easier for cost-effective
implementations.
4.
Layered Architecture Disadvantages
- Some layers functionality depends on the
information from the other layer and violates the goal of layer separation;
- One layer may duplicate lower layer functionalities
- Overhead both in computation
- Overhead in message headers caused by abstraction barriers between layers.
5.
OSI and Five-Layered Internet model Similarities
Many of the layers are the same
6.
OSI and Five-Layered Internet model Differences
- Three of the layers are
combined in the 5-layered model.
- Specifically the five-layer model combines the
- Application
- Presentation
- Session layers
from the OSI model into a single Application layer.
EXAM REVIEW MATERIAL Page 1
, 7.
What are sockets?
- A network socket is a software structure within a network
node of a computer network that serves as an endpoint for sending and receiving data
across the network.
- The structure and properties of a socket are defined by an application programming
interface (API) for the networking architecture.
- Sockets are created only during the lifetime of a process of an application running in
the node.
- ."A process sends messages into, and receives messages from, the network through a
software interface called a socket.
- Let's consider an analogy to help us understand processes and sockets. A process is
analogous to a house and its socket is analogous to its door....a socket is the interface
between the application layer and the transport layer within a host." - Kurose and Ross,
2.1
8.
Describe each layer of the OSI model.
- Application layer: Service, Interface,
Protocol.
- Presentation layer: Plays intermediate role of formatting the information received from
the layer below and delivering it to the application layer.
- Session layer: Responsible for the mechanism that manages the different transport
streams that belong to the same session between end-user and application process.
- Transport layer: Responsible for the end-to-end communication between end hosts.
Network layer: This layer is responsible for moving the packet of information, called a
datagram, from one host to another.
- Data Link layer: Responsible for moving the frames from one node (host or router) to
the next node.
- Physical layer: This layer is the actual hardware responsible to transfer bits within a
frame between two nodes c
9.
OSI Model Application Layer
- Service, Interface, Protocol.
Ex: Turn on your smartphone and look at the list of apps. (HTTP, SMTP, FTP, DNS)
10.
OSI Model Presentation Layer
- Plays intermediate role of formatting the
information received from the layer below and delivering it to the application layer.
Ex: converting big endian to little endian.
EXAM REVIEW MATERIAL Page 2
, 11.
OSI Model Session Layer
- Responsible for the mechanism that manages the
different transport streams that belong to the same session between end-user and
application process.
Ex: teleconference app, it is responsible for tying together audio and video streaming.
12.
OSI Model Network Layer
- This layer is responsible for moving the packet of
information, called a datagram, from one host to another.
- Responsible for delivering the datagram to the Transport layer on the destination host.
- In this layer there are the IP Protocol and the routing tables.
13.
OSI Model Transport Layer
- Responsible for the end-to-end communication
between end hosts.
- 2 protocols, TCP and UDP.
- TCP includes a connection-oriented service to the applications that are running on the
layer above, guaranteed delivery of the application-layer messages, flow control, and
congestion control mechanism.
- UDP provides a connectionless, best-effort service to the applications that are running
in the layer above without reliability, flow, or congestion control.
- In this layer the packet is called a segment.
14.
OSI Model Data Link Layer
- Packets are referred to as frames.
- Examples include:
- ethernet,
- ppp,
- wifi.
- Responsible for moving the frames from one node (host or router) to the next node.
- Services offered by the ___________ layer protocol include reliable delivery
(transmission of the data from one transmitting node, across one link, to the receiving
node.
EXAM REVIEW MATERIAL Page 3
, 15.
OSI Model Physical Layer
This layer is the actual hardware responsible to
transfer bits within a frame between two nodes c
16.
Provide examples of popular protocols at each layer of the five-layered Internet model.
Application: NFS, DNS, SNMP, ftp, rcp, telnet, HTTP
Transport: TCP, UDP
Internet: IP, ARP, ICMP
Data Link: PPP, IEEE 802.2, Ethernet
Physical Network: Token Ring, RS-232
17.
5-Layer Model - Transport Layer Protocols
- TCP- UDP
18.
5-Layer Model - Application Layer Protocols
- NFS
- DNS
- SNMP
- FTP
- RCP
- Telnet
- HTTP
19.
5-Layer Model - Internet Layer Protocols
- IP
- ARP
- ICMP
20.
5-Layer Model - Data Link Layer Protocols
- PPP
- IEEE 802.2
- Ethernet
21.
5-Layer Model - Physical Network Layer Protocols
- Token Ring
- RS-232
EXAM REVIEW MATERIAL Page 4
Questions and answers | Correct answers highlighted in green
1.
What are advantages and disadvantages of a layered architecture?
Each protocol
layer offers different services.
2.
Layered Architecture
Each protocol layer offers different services.
3.
Layered Architecture Advantages
- Scalability,
- Flexibility
- Ease of adding / removing components making it easier for cost-effective
implementations.
4.
Layered Architecture Disadvantages
- Some layers functionality depends on the
information from the other layer and violates the goal of layer separation;
- One layer may duplicate lower layer functionalities
- Overhead both in computation
- Overhead in message headers caused by abstraction barriers between layers.
5.
OSI and Five-Layered Internet model Similarities
Many of the layers are the same
6.
OSI and Five-Layered Internet model Differences
- Three of the layers are
combined in the 5-layered model.
- Specifically the five-layer model combines the
- Application
- Presentation
- Session layers
from the OSI model into a single Application layer.
EXAM REVIEW MATERIAL Page 1
, 7.
What are sockets?
- A network socket is a software structure within a network
node of a computer network that serves as an endpoint for sending and receiving data
across the network.
- The structure and properties of a socket are defined by an application programming
interface (API) for the networking architecture.
- Sockets are created only during the lifetime of a process of an application running in
the node.
- ."A process sends messages into, and receives messages from, the network through a
software interface called a socket.
- Let's consider an analogy to help us understand processes and sockets. A process is
analogous to a house and its socket is analogous to its door....a socket is the interface
between the application layer and the transport layer within a host." - Kurose and Ross,
2.1
8.
Describe each layer of the OSI model.
- Application layer: Service, Interface,
Protocol.
- Presentation layer: Plays intermediate role of formatting the information received from
the layer below and delivering it to the application layer.
- Session layer: Responsible for the mechanism that manages the different transport
streams that belong to the same session between end-user and application process.
- Transport layer: Responsible for the end-to-end communication between end hosts.
Network layer: This layer is responsible for moving the packet of information, called a
datagram, from one host to another.
- Data Link layer: Responsible for moving the frames from one node (host or router) to
the next node.
- Physical layer: This layer is the actual hardware responsible to transfer bits within a
frame between two nodes c
9.
OSI Model Application Layer
- Service, Interface, Protocol.
Ex: Turn on your smartphone and look at the list of apps. (HTTP, SMTP, FTP, DNS)
10.
OSI Model Presentation Layer
- Plays intermediate role of formatting the
information received from the layer below and delivering it to the application layer.
Ex: converting big endian to little endian.
EXAM REVIEW MATERIAL Page 2
, 11.
OSI Model Session Layer
- Responsible for the mechanism that manages the
different transport streams that belong to the same session between end-user and
application process.
Ex: teleconference app, it is responsible for tying together audio and video streaming.
12.
OSI Model Network Layer
- This layer is responsible for moving the packet of
information, called a datagram, from one host to another.
- Responsible for delivering the datagram to the Transport layer on the destination host.
- In this layer there are the IP Protocol and the routing tables.
13.
OSI Model Transport Layer
- Responsible for the end-to-end communication
between end hosts.
- 2 protocols, TCP and UDP.
- TCP includes a connection-oriented service to the applications that are running on the
layer above, guaranteed delivery of the application-layer messages, flow control, and
congestion control mechanism.
- UDP provides a connectionless, best-effort service to the applications that are running
in the layer above without reliability, flow, or congestion control.
- In this layer the packet is called a segment.
14.
OSI Model Data Link Layer
- Packets are referred to as frames.
- Examples include:
- ethernet,
- ppp,
- wifi.
- Responsible for moving the frames from one node (host or router) to the next node.
- Services offered by the ___________ layer protocol include reliable delivery
(transmission of the data from one transmitting node, across one link, to the receiving
node.
EXAM REVIEW MATERIAL Page 3
, 15.
OSI Model Physical Layer
This layer is the actual hardware responsible to
transfer bits within a frame between two nodes c
16.
Provide examples of popular protocols at each layer of the five-layered Internet model.
Application: NFS, DNS, SNMP, ftp, rcp, telnet, HTTP
Transport: TCP, UDP
Internet: IP, ARP, ICMP
Data Link: PPP, IEEE 802.2, Ethernet
Physical Network: Token Ring, RS-232
17.
5-Layer Model - Transport Layer Protocols
- TCP- UDP
18.
5-Layer Model - Application Layer Protocols
- NFS
- DNS
- SNMP
- FTP
- RCP
- Telnet
- HTTP
19.
5-Layer Model - Internet Layer Protocols
- IP
- ARP
- ICMP
20.
5-Layer Model - Data Link Layer Protocols
- PPP
- IEEE 802.2
- Ethernet
21.
5-Layer Model - Physical Network Layer Protocols
- Token Ring
- RS-232
EXAM REVIEW MATERIAL Page 4
