Computer Networks -Latest Exam
Questions and Answers
Which of the following descriptions below correspond to a "services" view of the Internet?
- ✔✔A platform for building network applications.
A place I go for information, entertainment, and to communicate with people.
A collection of billions of computing devices, and packet switches interconnected by links.
A collection of hardware and software components executing protocols that define the format
and the order of messages exchanged between two or more communicating entities, as well
as the actions taken on the transmission and/or receipt of a message or other event.
Which of the following human scenarios involve a protocol? - ✔✔One person asking,
and getting, the time to/from another person.
A person sleeping.
A person reading a book.
A student raising her/his hand to ask a really insightful question, followed by the teaching
acknowledging the student, listening carefully to the question, and responding with a clear,
insightful answer. And then thanking the student for the question, since teachers love to
get questions.
Two people introducing themselves to each other.
Which of the following physical layer technologies has the highest transmission rate and
lowest bit error rate in practice? - ✔✔Fiber optic cable
,Choose one the following two definitions that makes the correct distinction between
routing versus forwarding. - ✔✔Forwarding is the local action of moving arriving packets
from router's input link to appropriate router output link, while routing is the global action
of determining the source-destination paths taken by packets.
Routing is the local action of moving arriving packets from router's input link to appropriate
router output link, while forwarding is the global action of determining the source-
destination paths taken by packets.
Which of the characteristics below are associated with the technique of packet switching?
- ✔✔This technique is used in the Internet.
Resources are used on demand, not reserved in advance.
Data may be queued before being transmitted due to other user's data that's also queueing
for transmission.
This technique was the basis for the telephone call switching during the 20th century and
into the beginning of this current century.
Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) are
two approaches for implementing this technique.
Congestion loss and variable end-end delays are possible with this technique.
Reserves resources needed for a call from source to destination.
When we say that the Internet is a "network of networks," we mean? - ✔✔The Internet
is the largest network ever built.
The Internet is made up of a lot of different networks that are interconnected to each other.
The Internet is the fastest network ever built.
, The Internet is made up of access networks at the edge, tier-1 networks at the core, and
interconnected regional and content provider networks as well.
A network with three links, each with a transmission rate of 1 Mbps, and a propagation delay
of 1 msec per link. Assume the length of a packet is 1000 bits. What is the end-end delay of a
packet from when it first begins transmission on link 1, until is it received in full by the server at
the end of link 3. - ✔✔6 msec
A single source client sending to a server over two links of capacities R1=100 Mbps and
R3=10 Mbps. What is the maximum achievable end-end throughput (in Mbps, give an integer
value) for the client-to-server pair, assuming that the client is trying to send at its maximum
rate? - ✔✔10 Mbps
10 different servers (four shown) connected to 10 different clients over ten three-hop paths.
The pairs share a common middle hop with a transmission capacity of R = 200 Mbps. Each link
from a server has to the shared link has a transmission capacity of RS = 25 Mbps. Each link from
the shared middle link to a client has a transmission capacity of RC = 50 Mbps. What is the
maximum achievable end-end throughput (in Mbps, give an integer value) for each of ten
client-to-server pairs, assuming that the middle link is fairly shared and all servers are trying to
send at their maximum rate? - ✔✔20 Mbps
Suppose a packet is L = 1500 bytes long (one byte = 8 bits), and link transmits at R = 1 Gbps
(i.e., a link can transmit bits 1,000,000,000 bits per second). What is the transmission delay for
this packet? - ✔✔.000012 secs
10 different servers connected to 10 different clients over ten three-hop paths. The pairs share
a common middle hop with a transmission capacity of R = 300 Mbps. The four links from the
servers to the shared link have a transmission capacity of RS = 90 Mbps. Each of the four links
from the shared middle link to a client has a transmission capacity of RC = 50 Mbps. What is the
end-end maximum throughput on one of the the-hop paths, assuming all servers are sending at
the maximum rate possible to their clients? - ✔✔30 Mbps
Questions and Answers
Which of the following descriptions below correspond to a "services" view of the Internet?
- ✔✔A platform for building network applications.
A place I go for information, entertainment, and to communicate with people.
A collection of billions of computing devices, and packet switches interconnected by links.
A collection of hardware and software components executing protocols that define the format
and the order of messages exchanged between two or more communicating entities, as well
as the actions taken on the transmission and/or receipt of a message or other event.
Which of the following human scenarios involve a protocol? - ✔✔One person asking,
and getting, the time to/from another person.
A person sleeping.
A person reading a book.
A student raising her/his hand to ask a really insightful question, followed by the teaching
acknowledging the student, listening carefully to the question, and responding with a clear,
insightful answer. And then thanking the student for the question, since teachers love to
get questions.
Two people introducing themselves to each other.
Which of the following physical layer technologies has the highest transmission rate and
lowest bit error rate in practice? - ✔✔Fiber optic cable
,Choose one the following two definitions that makes the correct distinction between
routing versus forwarding. - ✔✔Forwarding is the local action of moving arriving packets
from router's input link to appropriate router output link, while routing is the global action
of determining the source-destination paths taken by packets.
Routing is the local action of moving arriving packets from router's input link to appropriate
router output link, while forwarding is the global action of determining the source-
destination paths taken by packets.
Which of the characteristics below are associated with the technique of packet switching?
- ✔✔This technique is used in the Internet.
Resources are used on demand, not reserved in advance.
Data may be queued before being transmitted due to other user's data that's also queueing
for transmission.
This technique was the basis for the telephone call switching during the 20th century and
into the beginning of this current century.
Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) are
two approaches for implementing this technique.
Congestion loss and variable end-end delays are possible with this technique.
Reserves resources needed for a call from source to destination.
When we say that the Internet is a "network of networks," we mean? - ✔✔The Internet
is the largest network ever built.
The Internet is made up of a lot of different networks that are interconnected to each other.
The Internet is the fastest network ever built.
, The Internet is made up of access networks at the edge, tier-1 networks at the core, and
interconnected regional and content provider networks as well.
A network with three links, each with a transmission rate of 1 Mbps, and a propagation delay
of 1 msec per link. Assume the length of a packet is 1000 bits. What is the end-end delay of a
packet from when it first begins transmission on link 1, until is it received in full by the server at
the end of link 3. - ✔✔6 msec
A single source client sending to a server over two links of capacities R1=100 Mbps and
R3=10 Mbps. What is the maximum achievable end-end throughput (in Mbps, give an integer
value) for the client-to-server pair, assuming that the client is trying to send at its maximum
rate? - ✔✔10 Mbps
10 different servers (four shown) connected to 10 different clients over ten three-hop paths.
The pairs share a common middle hop with a transmission capacity of R = 200 Mbps. Each link
from a server has to the shared link has a transmission capacity of RS = 25 Mbps. Each link from
the shared middle link to a client has a transmission capacity of RC = 50 Mbps. What is the
maximum achievable end-end throughput (in Mbps, give an integer value) for each of ten
client-to-server pairs, assuming that the middle link is fairly shared and all servers are trying to
send at their maximum rate? - ✔✔20 Mbps
Suppose a packet is L = 1500 bytes long (one byte = 8 bits), and link transmits at R = 1 Gbps
(i.e., a link can transmit bits 1,000,000,000 bits per second). What is the transmission delay for
this packet? - ✔✔.000012 secs
10 different servers connected to 10 different clients over ten three-hop paths. The pairs share
a common middle hop with a transmission capacity of R = 300 Mbps. The four links from the
servers to the shared link have a transmission capacity of RS = 90 Mbps. Each of the four links
from the shared middle link to a client has a transmission capacity of RC = 50 Mbps. What is the
end-end maximum throughput on one of the the-hop paths, assuming all servers are sending at
the maximum rate possible to their clients? - ✔✔30 Mbps
