OSI model and encapsulation Flashcards
Which layer of the OSI reference model contains the MAC and LLC
sublayers?
a. Network layer
b. Transport layer
c. Physical layer
d. Data link layer
Answer: d. The data link layer of the OSI model is the only layer of the
famous model that is typically divided into sublayers (the MAC and LLC
sublayers).
Which approach to bandwidth usage consumes all the available frequencies on
a medium to transmit data?
a. Broadband
b. Baseband
c. Time-division multiplexing
d. Simplex
Answer: b. Baseband technology uses the entire medium to transmit.
In contrast, broadband technology can divide the medium into different
channels. A great example of broadband is the use of the coaxial cable you
might have in your home, which carries cable television signals as well as
high-speed Internet.
Windowing is provided at what layer of the OSI reference model?
a. Data link layer
b. Network layer
c. Transport layer
d. Physical layer
Answer: c. The transport layer offers TCP and UDP. With TCP, a
connection-oriented protocol, windowing can be used to dictate how
much data is sent at one time.
IP addresses reside at which layer of the OSI reference model?
a. Network layer
b. Session layer
c. Data link layer
d. Transport layer
Answer: a. An IP address is a typical ingredient at the network layer
(Layer 3) of the OSI model. Routers use these addresses to route traffic
through an internetwork.
Which of the following is a connectionless transport layer protocol?
a. IP
b. TCP
c. UDP
d. SIP
Answer: c. User Datagram Protocol (UDP) sacrifices reliability for speed
and efficiency in the transport of data.
What setting ultimately controls the size of packets that are moving through
the modern network?
a. TTL
b. MTU
c. SSH
d. CSMA/CD
Answer: b. The maximum transmission unit (MTU) is the network
interface setting that defines the largest packet that may be sent onto the
network.
What is the range of well-known TCP and UDP ports?
a. Below 2048
b. Below 1024
c. 16,384–32,768
d. Above 8192
Answer: b. The well-known port numbers are all below 1024. An example
would be HTTP (WWW) at port 80.
What port number is used by HTTPS?
a. 80
b. 443
c. 69
d. 23
Answer: b. HTTPS uses TCP port 443 in its operation. Contrast this to
HTTP (that offers no security) and used port 80.
What value is decremented by one for each router hop on the network?
a. Count
b. Type
c. TTL
d. Dead timer
Answer: c. The TTL value of the IP packet is decremented for each
router hop. This is a loop prevention mechanism.
Windowing is a technology that applies to which transport layer protocol?
a. UDP
b. FTP
c. ICMP
d. TCP
Answer: d. The connection-oriented TCP uses several techniques to
ensure reliability in the communications. Windowing is one of those.
What happens to data as it moves from the upper layers to the lower layers of
the OSI model on a host system?
a. The data moves from the physical layer to the application layer.
b. The data is encapsulated with a header at the beginning and a trailer at
the end.
c. The header and trailer are stripped off through decapsulation.
d. The data is sent in groups of segments that require two
acknowledgments.
Answer: b. As data moves down through the OSI model layers (on a host),
it is encapsulated with a header added to the beginning and a trailer to the end. When the data arrives at the receiving host, it moves up the model
and is decapsulated in that the header and trailer are stripped off as it moves
up though the OSI layers.
Which layer of the OSI reference model is responsible for ensuring that
frames do not exceed the maximum transmission unit (MTU) of the physical
media?
a. Network layer
b. Transport layer
c. Physical layer
d. Data link layer
Answer: d. The data link layer is concerned with packaging data into frames
and ensuring that frames do not exceed the maximum transmission unit
(MTU) of the physical media.
