WorksheetsFINAL EXAMINATION IN CS 314 (Networks and Communication)
Total questions: 43
Worksheet time: 1hrs 10mins
Which layer in TCP/IP is responsible for end-to-end communication??
Physical
Application
Transport
Network Access
What is the main function of the Internet layer?
File transfer
Application logic
Routing data between networks
Signal encoding
In data transmission, which protocol ensures reliable delivery?
UDP
TCP
IP
SMTP
Why is a checksum included in TCP segment headers?
Addressing routing
Detecting transmission errors
Speed optimization
Congestion control
Which protocol uses a connectionless transport?
TCP
UDP
FTP
SMTP
What distinguishes IPv6 addresses from IPv4?
128-bit length
Error control field
Port addressing
End-to-end reliability
Sequence numbers in TCP segments are used for:
Port selection
Reordering packets
Addressing hosts
Flow control
Which protocol provides user authentication in remote logins?
SMTP
FTP
TELNET
SNMP
Which layer interacts directly with a transmission medium?
Network Access
Internet
Transport
Application
What is the key purpose of the Protocol field in IP headers?
Indicate destination address
Specify data rate
Select the upper protocol
Error checking
Fragmentation and reassembly in IP is handled by:
The transport layer
Sequence numbers
Fragment offset fields
Ports
In TCP/IP, the logical connection refers to:
Bit stream transfer
Address resolution
Pair of port values
Host address mapping
What does UDP lack that TCP provides?
Congestion control
Reliable delivery
Port addressing
Header checksum
In Bellman-Ford, what type of information does each node use to calculate costs?
Only centralized routing tables
All neighbor node costs
Only outgoing link information
Full global topology at initialization
Why might adaptive routing sometimes reduce network efficiency?
Adaptive routing never responds to congestion
Frequent updates add overhead
Fixed routes adapt instantly
Flooding balances queues better
When constructing routing tables using Dijkstra’s algorithm, what does each router require?
Only local link information
Complete network topology and link costs
Purely random link selection
Static neighbor vectors
What is path-vector routing’s unique contribution compared to link-state and distance-vector routing?
Allows full topology reconstruction
Transmits paths traversed, enabling policy routing
Ignores network congestion
Favors neighbor selection exclusively
Fixed routing is most suitable under which scenario?
Network topology changes frequently
Network is reliable and stable
High congestion is expected
Packet duplication is needed
What impact does the transmission of frequent routing information have on the network?
It always increases network efficiency
It adds processing overhead and can reduce efficiency
Only virtual circuits benefit
Reduces robustness unconditionally
In evaluating routing strategies, which trade-off is involved with fairness and optimality?
Greater fairness increases throughput
Optimization may disadvantage distant communication
Fairness always improves robustness
Optimal paths bypass congestion
What best explains least-cost routing in modern packet-switching networks?
Always the path with fewest hops
Path cost accumulates based on predefined metrics per link
Each link is treated as zero-cost
Routing is only random
What problem arises when queue length is the only delay metric in routing?
High-capacity links remain underutilized
All nodes become centralized
Only stub networks are routed
Update messages decrease
Which comparison of Dijkstra’s and Bellman-Ford algorithms is accurate?
Dijkstra’s needs global topology; Bellman-Ford needs neighbor costs
Bellman-Ford ignores link weight
Dijkstra’s is more prone to instability
Both only work with static link costs
In a WiFi network, the device that coordinates data transmissions and client associations is called what?
(a)
What unique identifier do WiFi networks use for association?
(a)
In the IEEE 802.11 protocol, the process of a device joining with an Access Point is called what?
(a)
The 32-bit field in WiFi frames used for error detection is called what?
(a)
When a device moves from one cell to another in a cellular network, what is the process called?
(a)
In wireless networking, a group of devices communicating without a centralized access point forms what type of network?
(a)
The MAC protocol for WiFi, which avoids collisions rather than detecting them, is called what?
(a)
The frequency bands most commonly used by WiFi networks are ________ GHz and ________ GHz?
(a)
The protocol used in cellular networks to create tunnels for mobility management is called what?
(a)
In LTE, the network component that authenticates and authorizes users is called what?
(a)
The process by which a WiFi device scans for APs using their beacon frames is known as what type of scanning?
(a)
The first step in a cellular device attachment phase involves connecting to a nearby what?
(a)
A wireless station that sends multiple copies of a frame differentiates these using which field?
(a)
What technique adapts the transmission rate of WiFi according to channel conditions?
(a)
In 802.11 frames, which field specifies how long the channel will be reserved for transmission?
(a)
What is the main multiplexing technique used for downlink channels in LTE?
(a)
Which higher-layer protocol struggles with packet losses from wireless errors and handovers?
(a)
Decipher the below Ciphertext using the Transposition Cipher Algorihtm:
Key=CRYPTO
Ciphertext = t t t y s a r a e i e i n s c a s x o w e t t s a m f e p e s i t e m a d h e i t t m e l s a r n c o e w a e t e h n a l v e f v o h i v l s l i a e
(a)
Decipher the Ciphertext using One-time Pad Algorithm.
ONE-TIME PAD Key= A G H T E F I L O R U K A S D E H I U Q H I L R
Ciphertext = N K A P S W S D O E X M O E P Y U Q W Q A Q Z E
(a)
RSA Decryption:
Given a simplified RSA cryptosystem with:
Modulus: n=33
Private exponent: d=7
A ciphertext message has been received, with each ciphertext number calculated using encryption rule C=P3 mod33
Task:
Use the decryption rule P=C7 mod 33 to recover the original plaintext numbers from the following ciphertext sequence.
2187 1 10460353203 8031810176 27512614111 105413504 410338673 8031810176 612220032 2187 78125 1 35831808 8031810176 21870000000 1 893871739
(a)
