COMPUTER NETWORKING EXAM 1 | CS6250 EXAM 1 | QUESTIONS
AND ANSWERS | VERIFIED ANSWERS GRADED A+ | LATEST EXAM
UPDATE
What is a big issue in computer networking?
scalability
network
general examples: computer network, water network, sewer system, cable
tv, phones
- all special-purpose
computer network
- general purpose network
- not optimal since general purpose
- does many things, but less optimal as a result
stakeholders
people who use the network
What are we most concerned with sharing, and what is its drawback?
- the network itself
- expensive
Internet Service Provider (ISP)
company that provides access to internet
What is an example of a common service in a computer network?
file sharing
What are the two general approach/architectures of networks?
- Telco Model
- aka bellheads, circuit switched network
- Post Office Model
- aka netheads; packet switched network
,Telco Model process
- request network set up a connection
- send/receive messages
- teardown the connection
How does the Telco Model work?
- computer networks use same principle as old phones: pair of wires
reserved for sender/receiver, and sometimes the wires weren't available
- setup overhead; if resources aren't available, refuse the connection
- during connection, messages don't need the destination address (messages
don't carry the destination address)
- Plain Old Telephones (POTS) ex.: used switches at certain centralized
points in the network, which functioned as communication nodes b/w two
points in a network
- network already made decision (chose destination address) when link was
being set up
- teardown overhead
forwarding decision
deciding the next destination
hops
different destination stops; switches in a network
How do forwarding decisions and hops work together?
Address is examined at each hop to determine where it goes next, which is
the forwarding decision.
How does the Post Office Model work?
- more accurate to computer networks today
- still a switched network, but instead of circuits, packets
- no request to reserve resources for message
- message is directly injected into network (hope for the best)
- like a postcard (packet/message must contain destination address)
- uses forwarding decisions and hops
- no setup required, so no teardown, resulting in no setup/teardown
overhead
- instead, overhead at each switch/hop (forwarding overhead)
,T/F: The destination address is carried in messages with the Telco Model,
but not with the Post Office Model.
F; opposite
Bellheads vs. Netheads
- bellheads wanted endpoints to be simple, but networks to be complex and
overarching (how phones still work)
- netheads wanted endpoints to be complex, but networks to be simple (just
wanted network to move bits)
What does computer network architecture lead to?
layering and protocols
What cuts down on interference?
twisting wires together (twisted pair)
What happens as signals propagate over a wire?
they get weaker
How can you decompose network architecture into something more
manageable?
use layering
OSI (Open Systems Interconnection) Model
- International Standards Organization created this protocol reference
model
- 7 layer model; not way we implement computer networks, but how we
talk about them
- great reference model, but not in practice
- when decomposing the layers, it starts at the bottom layer and goes all the
way down to the top layer
What are the 7 layers in the OSI Model?
1. Physical Layer: putting bits on the "wire"
2. Data Link Layer: error detection and reliability
3. Network Layer: host-to-host
4. Transport Layer: process-to-process (program in execution)
5. Session Layer: handles sessions (gets absorbed)
6. Presentation Layer: formatting (not all computer formats are the same)
7. Application Layer: user (programmer) interface
, What is an phrase that can help you remember the OSI Model's 7 layers?
Please Do Not Take Sausage Pizza Away
What are the two types of connectivity?
direct connectivity and indirect connectivity
direct connectivity
running wire between systems
indirect connectivity
still connected, but wire isn't necessarily connected
nodes
any computational device connected to a network
link
"wire" used to move bits across the network
network topology
different ways computers are connected
- some type of node connects them
What are the two forms of network topology?
- point-to-point
- multi-point
point-to-point
direct connection
multi-point (multi-access)
direct connection between many nodes
network edge
nodes between networks
ex. router/modem
channel
logical path from one node to another
cloud (not the same as "the cloud")
AND ANSWERS | VERIFIED ANSWERS GRADED A+ | LATEST EXAM
UPDATE
What is a big issue in computer networking?
scalability
network
general examples: computer network, water network, sewer system, cable
tv, phones
- all special-purpose
computer network
- general purpose network
- not optimal since general purpose
- does many things, but less optimal as a result
stakeholders
people who use the network
What are we most concerned with sharing, and what is its drawback?
- the network itself
- expensive
Internet Service Provider (ISP)
company that provides access to internet
What is an example of a common service in a computer network?
file sharing
What are the two general approach/architectures of networks?
- Telco Model
- aka bellheads, circuit switched network
- Post Office Model
- aka netheads; packet switched network
,Telco Model process
- request network set up a connection
- send/receive messages
- teardown the connection
How does the Telco Model work?
- computer networks use same principle as old phones: pair of wires
reserved for sender/receiver, and sometimes the wires weren't available
- setup overhead; if resources aren't available, refuse the connection
- during connection, messages don't need the destination address (messages
don't carry the destination address)
- Plain Old Telephones (POTS) ex.: used switches at certain centralized
points in the network, which functioned as communication nodes b/w two
points in a network
- network already made decision (chose destination address) when link was
being set up
- teardown overhead
forwarding decision
deciding the next destination
hops
different destination stops; switches in a network
How do forwarding decisions and hops work together?
Address is examined at each hop to determine where it goes next, which is
the forwarding decision.
How does the Post Office Model work?
- more accurate to computer networks today
- still a switched network, but instead of circuits, packets
- no request to reserve resources for message
- message is directly injected into network (hope for the best)
- like a postcard (packet/message must contain destination address)
- uses forwarding decisions and hops
- no setup required, so no teardown, resulting in no setup/teardown
overhead
- instead, overhead at each switch/hop (forwarding overhead)
,T/F: The destination address is carried in messages with the Telco Model,
but not with the Post Office Model.
F; opposite
Bellheads vs. Netheads
- bellheads wanted endpoints to be simple, but networks to be complex and
overarching (how phones still work)
- netheads wanted endpoints to be complex, but networks to be simple (just
wanted network to move bits)
What does computer network architecture lead to?
layering and protocols
What cuts down on interference?
twisting wires together (twisted pair)
What happens as signals propagate over a wire?
they get weaker
How can you decompose network architecture into something more
manageable?
use layering
OSI (Open Systems Interconnection) Model
- International Standards Organization created this protocol reference
model
- 7 layer model; not way we implement computer networks, but how we
talk about them
- great reference model, but not in practice
- when decomposing the layers, it starts at the bottom layer and goes all the
way down to the top layer
What are the 7 layers in the OSI Model?
1. Physical Layer: putting bits on the "wire"
2. Data Link Layer: error detection and reliability
3. Network Layer: host-to-host
4. Transport Layer: process-to-process (program in execution)
5. Session Layer: handles sessions (gets absorbed)
6. Presentation Layer: formatting (not all computer formats are the same)
7. Application Layer: user (programmer) interface
, What is an phrase that can help you remember the OSI Model's 7 layers?
Please Do Not Take Sausage Pizza Away
What are the two types of connectivity?
direct connectivity and indirect connectivity
direct connectivity
running wire between systems
indirect connectivity
still connected, but wire isn't necessarily connected
nodes
any computational device connected to a network
link
"wire" used to move bits across the network
network topology
different ways computers are connected
- some type of node connects them
What are the two forms of network topology?
- point-to-point
- multi-point
point-to-point
direct connection
multi-point (multi-access)
direct connection between many nodes
network edge
nodes between networks
ex. router/modem
channel
logical path from one node to another
cloud (not the same as "the cloud")
