WorksheetsNetworking Quiz
Total questions: 100
Worksheet time: 50mins
A company has two offices. Office A uses network 192.168.1.0/24 and Office B uses network 192.168.1.0/24. When they connect both offices via a VPN, devices cannot communicate properly. What is the problem and how should it be solved?
The VPN is not configured correctly; reconfigure the VPN.
Both offices use the same subnet; change one office's subnet.
The devices are not compatible with VPN; replace the devices.
The switch is faulty; replace the switch.
A technician configures PC-A with IP 192.168.10.65/26 and PC-B with IP 192.168.10.130/26. Both are connected to the same switch. PC-A cannot ping PC-B. The technician believes the switch is faulty. Is this correct? Explain.
Yes, the switch is faulty; replace it.
No, the IP addresses are in different subnets; reconfigure the IPs.
Yes, the switch is faulty; reset it.
No, the devices are incompatible; replace them.
An administrator needs to create 4 subnets from network 10.0.0.0/8. A junior technician suggests using /10 mask. A senior technician suggests using /30 mask. Which is more appropriate and why?
/10 mask is appropriate; it provides enough addresses for subnets.
/30 mask is appropriate; it provides more subnets.
/10 mask is inappropriate; it provides too few subnets.
/30 mask is inappropriate; it provides too few addresses per subnet.
Host A (10.1.1.50/16) sends a packet to Host B (10.2.1.50/16). No router exists between them. Will the communication succeed? Explain your reasoning.
Yes, they are in the same subnet.
No, they are in different subnets.
Yes, they are directly connected.
No, the IP addresses are invalid.
A network uses 172.16.0.0/16. The administrator creates subnet 172.16.5.0/24 for Sales. Later, Finance needs a subnet for only 10 hosts. Can the administrator use 172.16.5.128/28 from the original /16? Why or why not?
Yes, it provides enough addresses for Finance.
No, it overlaps with the Sales subnet.
Yes, it is part of the original /16.
No, it is not part of the original /16.
A router has an interface with IP 192.168.1.1/24. A host on that network is configured with IP 192.168.1.1/24. What will happen and why?
The host will communicate normally.
The host will experience IP conflict; reconfigure the host's IP.
The router will block the host's communication.
The host will communicate with limited functionality.
Wireshark capture shows two packets from the same source: Packet 1 - ID: 0x5F3A, Flags: 0x20 (More Fragments), Offset: 0, Length: 1500. Packet 2 - ID: 0x5F3A, Flags: 0x00, Offset: 185, Length: 700. What can you conclude?
The packets are part of the same fragmented message.
The packets are unrelated and from different sources.
The packets indicate a routing loop.
The packets are corrupted and cannot be analyzed.
Analyze this routing table entry: S 10.10.0.0/16 [1/0] via 192.168.1.1. A packet arrives for destination 10.10.50.25. Another entry shows: S 10.10.50.0/24 [1/0] via 192.168.1.2. Which path will the packet take and why?
The packet will take the path via 192.168.1.1 because it has a lower metric.
The packet will take the path via 192.168.1.2 because it matches a more specific route.
The packet will be dropped because no valid route exists.
The packet will take the path via 192.168.1.1 because it is the default route.
Routing table shows: C 192.168.1.0/24 is directly connected, GigabitEthernet0/0 and S 0.0.0.0/0 [1/0] via 192.168.1.254. A packet arrives for 192.168.1.50. Which route is used and why?
The route via 192.168.1.254 is used because it has a lower metric.
The directly connected route is used because it matches the destination IP.
The packet is dropped because no valid route exists.
The route via 192.168.1.254 is used because it is the default route.
Wireshark shows: Source IP: 192.168.1.50, Source MAC: AA:BB:CC:DD:EE:01, Destination IP: 10.0.0.100, Destination MAC: AA:BB:CC:DD:EE:99. The capture was taken on the source host's network. What is AA:BB:CC:DD:EE:99?
The MAC address of the source host.
The MAC address of the destination host.
The MAC address of the router.
The MAC address of the switch.
Wireshark IP header shows: Source: 10.0.0.5, Destination: 10.0.0.255, Protocol: 1. The network is 10.0.0.0/24. What is Protocol: 1 and what is the purpose of this packet?
Protocol 1 indicates TCP, and the packet is used for data transfer.
Protocol 1 indicates UDP, and the packet is used for streaming.
Protocol 1 indicates ICMP, and the packet is used for network diagnostics.
Protocol 1 indicates ARP, and the packet is used for address resolution.
A router's routing table shows: S 192.168.0.0/22 [1/0] via 10.0.0.1. A packet arrives for destination 192.168.5.100. Will this route be used? Explain.
Yes, because the destination matches the route.
No, because the destination is outside the route's range.
Yes, because the route has the lowest metric.
No, because the route is inactive.
A host sends a ping to a remote server. After some time, it receives an ICMP message with Type 11, Code 0. What does this tell the administrator about the network path?
The destination host is unreachable.
The packet was dropped due to TTL expiration.
The server is not responding to pings.
The network is experiencing congestion.
Network documentation shows a subnet mask as 0xFFFFFF00. An administrator needs to configure a device that only accepts dotted decimal format. What should be entered?
255.255.255.0
255.255.0.0
255.0.0.0
255.255.255.255
Determine the number of hosts that can exist in a /20 network.
4096 hosts
2048 hosts
8192 hosts
1024 hosts
An administrator pings a host and receives the reply "Destination Host Unreachable" from the local router (192.168.1.1). What does this indicate compared to receiving no response at all?
The host is powered off.
The router cannot find a route to the destination.
The host is unreachable due to a firewall.
The host is reachable but not responding.
A packet arrives at a router with TTL=0. What does the router do and why might this situation occur?
Drops the packet and sends an ICMP Time Exceeded message.
Forwards the packet to the next hop.
Resets the TTL value and forwards the packet.
Sends the packet back to the source.
Wireshark shows a packet with Protocol field = 6. What protocol is being used above the IP layer?
UDP
TCP
ICMP
ARP
A routing table shows: O IA 10.1.0.0/16 [110/30] via 192.168.1.1. What does IA indicate about this route?
It is an internal route.
It is an inter-area route.
It is an external route.
It is a static route.
Host A (192.168.1.10/24) sends data to Host B (192.168.2.10/24). The packet leaves Host A with destination MAC set to Host A's default gateway. Why?
Host B is unreachable.
Host A is configured incorrectly.
The packet is routed through the default gateway.
Host A and Host B are on the same subnet.
A router receives packets for 10.0.0.0/8 and has two equal-cost paths. What is this called and what happens?
Load balancing; packets are distributed across both paths.
Routing loop; packets are dropped.
Static routing; packets follow a single path.
Default routing; packets are sent to the default gateway.
An IP packet has Total Length: 576, IHL: 5, and 20 bytes of options. Are these values consistent?
Yes, the values are consistent.
No, the Total Length is incorrect.
No, the IHL value is incorrect.
No, the options length is incorrect.
Wireshark shows TCP RST flag set. Source port 80, destination port 45678. What likely happened?
The connection was successfully established.
The connection was reset by one of the endpoints.
The connection experienced packet loss.
The connection was terminated normally.
Wireshark shows TCP options: MSS=1460, SACK permitted, Window Scale=7. What do these options tell you about the connection?
The connection is using UDP.
The connection supports large data transfers and selective acknowledgments.
The connection is encrypted.
The connection is experiencing high latency.
Wireshark shows source port 53, destination port 49152, protocol UDP. What application is likely involved?
HTTP
DNS
FTP
SMTP
A capture shows: UDP datagram to port 161. Response comes from port 161 to the original source port. What protocol is this?
HTTP
SNMP
FTP
SMTP
Wireshark shows ICMP Port Unreachable (Type 3, Code 3) following a UDP packet. What happened?
The destination port is open.
The destination port is closed.
The packet was successfully delivered.
The packet was dropped due to congestion.
A TCP capture shows window size going from 65535 to 32768 to 16384 to 0 across several segments. What is happening?
The connection is being reset.
The receiver is running out of buffer space.
The sender is experiencing packet loss.
The connection is idle.
A capture shows TCP retransmission after 200ms, then 400ms, then 800ms. What pattern is this?
Exponential backoff
Linear retransmission
Random retransmission
Immediate retransmission
A UDP header shows Length: 8. Is this valid? What does it mean?
The packet is invalid.
The packet contains only the header with no data.
The packet is encrypted.
The packet is fragmented.
Wireshark shows duplicate ACKs: Ack=5000, Ack=5000, Ack=5000. What is the receiver signaling?
Packet loss
Connection termination
Successful data transfer
High latency
A capture shows SACK blocks: 6000-6500, 7000-7500. The ACK number is 5000. What has been received?
Data up to 5000
Data up to 7500
Data up to 6500
Data up to 7000
Wireshark shows TCP PSH flag set on a segment. What does this indicate and when is it typically used?
The connection is being reset.
The sender is signaling urgent data.
The sender is pushing data to the application layer.
The connection is idle.
Wireshark capture shows a TCP connection with consistently high RTT (500ms+) but no packet loss. What might cause this?
Network congestion
Long physical distance between endpoints
Packet corruption
High bandwidth availability
UDP checksum calculation includes a pseudo-header with source IP, dest IP, protocol, length. Why include IP addresses in a transport layer checksum?
To verify the integrity of the transport layer data.
To ensure the packet is routed correctly.
To detect corruption in the IP header.
To identify the sender and receiver.
A developer asks: Why does DNS use UDP while HTTP uses TCP? Explain the fundamental transport needs that drive this choice.
DNS requires reliable delivery, while HTTP does not.
DNS is faster and does not require connection establishment.
HTTP is slower and requires connection establishment.
DNS uses encryption, while HTTP does not.
Two applications on the same host both try to bind() to TCP port 8080. The second bind() fails with Address already in use. Why does the OS prevent this, and what would happen if it were allowed?
To prevent data corruption; multiple applications could receive the same data.
To ensure high bandwidth availability.
To allow multiple applications to share the same port.
To prevent packet loss.
A client socket is identified by 4-tuple (192.168.1.10, 50000, 10.0.0.1, 80). The client host has one network interface. Can the same client create another connection with 4-tuple (192.168.1.10, 50000, 10.0.0.2, 80)?
Yes, because the destination IP is different.
No, because the source port is the same.
Yes, because the source IP is the same.
No, because the destination port is the same.
Server runs on well-known port 80. Client connects from ephemeral port 52000. Why are port ranges divided into well-known (0-1023), registered (1024-49151), and dynamic/ephemeral (49152-65535)?
To ensure efficient routing of packets.
To differentiate between server and client ports.
To prevent port conflicts between applications.
To allow encryption of data.
Wireshark shows TCP segment: Source Port: 443, Dest Port: 51234, Seq: 1000, Ack: 5000, Flags: ACK, PSH. What does the PSH flag tell us about this data and what should the receiver do?
The PSH flag indicates the data is urgent and should be processed immediately.
The PSH flag signals the receiver to wait for more data before processing.
The PSH flag tells the receiver to flush the buffer and process the data immediately.
The PSH flag is used to indicate a connection termination.
An application developer creates a UDP socket and sends a 10,000-byte message. The developer expects one recv() call to receive all 10,000 bytes. Will this work? How does UDP handle large messages compared to TCP?
UDP guarantees delivery of large messages in one recv() call.
UDP splits large messages into smaller packets, which may arrive out of order.
UDP uses flow control to ensure large messages are received in one call.
UDP does not support sending messages larger than 1,000 bytes.
A firewall administrator sees thousands of half-open TCP connections (SYN received, SYN-ACK sent, no final ACK). The server is slow and memory is exhausted. Explain this attack and why it targets the transport layer specifically.
This is a SYN flood attack targeting the transport layer to exhaust server resources.
This is a DNS spoofing attack targeting the transport layer to redirect traffic.
This is a UDP flood attack targeting the transport layer to overload the server.
This is an ARP poisoning attack targeting the transport layer to disrupt communication.
DNS uses UDP port 53 for queries, but sometimes uses TCP port 53. Under what circumstances does DNS switch to TCP, and why not use TCP always?
DNS switches to TCP for large responses or zone transfers.
DNS switches to TCP when UDP is unavailable.
DNS switches to TCP for encrypted communication.
DNS switches to TCP for faster query resolution.
A user sends email from alice@gmail.com to bob@yahoo.com. The email travels through multiple servers. Which protocol is used between Gmail's server and Yahoo's server, and why is this different from what Bob uses to read the email?
SMTP is used between servers, while Bob uses POP3 or IMAP to read the email.
IMAP is used between servers, while Bob uses SMTP to read the email.
POP3 is used between servers, while Bob uses IMAP to read the email.
HTTP is used between servers, while Bob uses SMTP to read the email.
When a browser makes an HTTPS request to port 443, the HTTP content is encrypted. But TCP and IP headers remain unencrypted. Why can't we encrypt everything including port numbers and IP addresses?
Encrypting TCP and IP headers would prevent routing and delivery of packets.
Encrypting TCP and IP headers is unnecessary for security.
Encrypting TCP and IP headers would slow down communication.
Encrypting TCP and IP headers is technically impossible.
HTTP uses human-readable text format (GET /index.html HTTP/1.1). DNS also uses a specific message format. Why do application layer protocols define their own message formats instead of using a universal format?
Application layer protocols define formats to optimize for specific use cases.
Universal formats are too complex for application layer protocols.
Application layer protocols use unique formats to ensure security.
Universal formats are incompatible with network protocols.
What is the purpose of the TTL (Time To Live) field in an IP packet?
To determine the size of the packet
To prevent packets from looping indefinitely
To identify the source of the packet
To encrypt the packet data
A router receives a packet for destination 10.5.5.5. The routing table has: 10.0.0.0/8 via 192.168.1.1, 10.5.0.0/16 via 192.168.1.2, 10.5.5.0/24 via 192.168.1.3. Which route is selected?
10.0.0.0/8 via 192.168.1.1
10.5.0.0/16 via 192.168.1.2
10.5.5.0/24 via 192.168.1.3
None of the above
What is a default route and when is it used?
A route used for local traffic only
A route used when no specific route matches the destination
A route used for encrypted traffic
A route used for multicast traffic
What is the difference between a routing table in a router and a routing table in a regular computer (host)?
Routers have static tables, while hosts have dynamic tables
Routers handle network traffic, while hosts handle local traffic
Routers use routing tables for forwarding packets, while hosts use them for selecting the default gateway
Routers use tables for encryption, while hosts use them for decryption
What does TCP provide that UDP does not?
Faster data transmission
Connectionless communication
Reliable data delivery and error checking
Support for multicast traffic
What is DNS and why is it necessary for internet communication?
DNS encrypts internet traffic
DNS translates domain names into IP addresses
DNS provides faster internet speeds
DNS blocks malicious websites
What is the difference between HTTP and HTTPS?
HTTPS uses encryption, while HTTP does not
HTTP is faster than HTTPS
HTTPS is used for local networks only
HTTP supports multimedia, while HTTPS does not
HTTP/1.0 opens a new TCP connection for each request. HTTP/1.1 introduced persistent connections. Why is this more efficient?
It reduces the number of connections needed
It increases the speed of encryption
It allows for larger packet sizes
It improves error detection
Alice sends email to bob@company.com. Alice's mail server needs to find company.com's mail server. What DNS query does Alice's server make?
MX record query
A record query
CNAME record query
PTR record query
A peer-to-peer (P2P) application lets users share files directly. How does this differ from the client-server model?
P2P applications rely on centralized servers for file sharing.
P2P applications distribute files directly between users without a central server.
P2P applications use DNS for file sharing.
P2P applications require a dedicated server for file sharing.
A browser requests a page and receives: HTTP/1.1 301 Moved Permanently, Location: https://www.example.com/. What should the browser do?
Display an error message.
Redirect to the new URL provided in the Location header.
Retry the request to the same URL.
Ignore the response and close the connection.
A user visits a website. The browser shows the page but some images show broken icons. What might have happened at the DNS or HTTP level?
The DNS server failed to resolve the image URLs.
The HTTP server returned a 404 error for the images.
The images were blocked by the browser's security settings.
The images were cached incorrectly by the browser.
A company's website is www.company.com and their mail server is mail.company.com. In DNS, what records would exist for this setup?
A record for www.company.com and MX record for mail.company.com.
CNAME record for www.company.com and PTR record for mail.company.com.
MX record for www.company.com and A record for mail.company.com.
TXT record for www.company.com and SRV record for mail.company.com.
TCP guarantees reliable delivery. If a segment is lost, how does TCP know to retransmit it?
TCP uses a timer to detect lost segments and retransmits them.
TCP relies on the application layer to request retransmission.
TCP uses UDP to retransmit lost segments.
TCP does not retransmit lost segments.
UDP does not guarantee delivery. Why doesn't UDP simply add reliability like TCP?
UDP is designed for applications that require low latency and high speed.
UDP cannot implement reliability due to protocol limitations.
UDP relies on TCP for reliability.
UDP is only used for DNS queries.
What is the basic purpose of NAT (Network Address Translation)?
To assign public IP addresses to all devices in a network.
To allow multiple devices to share a single public IP address.
To encrypt data transmitted over the internet.
To block unauthorized access to a network.
A packet from the internet arrives at a NAT router destined for a private host. How does the router know which internal device should receive it?
The router uses a static routing table.
The router uses port numbers to map the packet to the correct device.
The router broadcasts the packet to all devices.
The router uses DNS to resolve the device's IP address.
Why are private IP address ranges (10.x.x.x, 172.16.x.x, 192.168.x.x) not routable on the internet?
They are reserved for internal use and cannot be used publicly.
They are blocked by firewalls.
They are encrypted and cannot be routed.
They are only used for DNS queries.
Two computers in the same room can communicate, but a computer in another building cannot join the conversation. What determines whether devices can communicate on a network?
Network topology
Network protocols
Network bandwidth
Network latency
A company has computers connected with cables, but they still cannot share files. What essential component might be missing?
Network switch
Network router
Network software
Network hub
Two companies use different email systems. Company A uses System X, Company B uses System Y. Yet employees can send emails between companies. How is this possible?
Email protocols
Shared network topology
Common bandwidth
Unified IP addresses
A home user connects a new laptop to their Wi-Fi. Without any manual configuration, the laptop gets an IP address and can browse the internet. What made this automatic configuration possible?
DNS
DHCP
HTTP
FTP
What is the difference between the Internet and the World Wide Web (WWW)?
The Internet is hardware; the WWW is software
The Internet is a network; the WWW is a service
The Internet is global; the WWW is local
The Internet uses IP; the WWW uses HTTP
Why do network protocols typically operate in layers rather than as a single monolithic system?
To simplify troubleshooting
To increase bandwidth
To reduce latency
To improve hardware compatibility
What does it mean when we say the Internet uses packet switching?
Data is sent in continuous streams
Data is divided into packets and sent independently
Data is compressed before transmission
Data is encrypted during transmission
A user complains: My file download started fast but then slowed down. How does packet switching explain this behavior?
Packets are lost during transmission
Packets are delayed due to congestion
Packets are corrupted during transmission
Packets are rerouted to different servers
What is the primary function of a router in a network?
To connect devices within a local network
To forward data between different networks
To store data for backup purposes
To increase network bandwidth
A network has 20 computers connected to a hub. When Computer A sends data to Computer B, what happens?
The hub sends the data directly to Computer B
The hub broadcasts the data to all computers
The hub encrypts the data before sending
The hub compresses the data before sending
What is bandwidth in networking terms?
The speed of data transmission
The amount of data that can be transmitted per second
The delay in data transmission
The reliability of data transmission
What is the difference between bandwidth and throughput?
Bandwidth is theoretical; throughput is actual
Bandwidth is actual; throughput is theoretical
Bandwidth measures latency; throughput measures speed
Bandwidth measures reliability; throughput measures efficiency
A user in London plays an online game with a server in Tokyo. They experience lag despite having high bandwidth. What network characteristic explains this?
Packet loss
Latency
Bandwidth congestion
Network topology
What is packet loss and why does it occur?
Data packets are corrupted during transmission
Data packets are dropped due to network congestion
Data packets are delayed due to latency
Data packets are rerouted to different servers
Why do network engineers consider both bandwidth AND latency when designing networks?
To ensure data is transmitted quickly and reliably
To reduce the cost of network infrastructure
To increase the number of connected devices
To improve network security
What are network protocols HTTP, HTTPS, and FTP used for?
Encrypting data
Transmitting data over the internet
Compressing data
Storing data
A user types www.university.edu in their browser. The browser has never visited this site. What must happen before the webpage can load?
The browser must resolve the IP address using DNS
The browser must establish a direct connection to the server
The browser must compress the webpage data
The browser must encrypt the webpage data
What is a client-server model in networking?
A model where all devices are equal
A model where one device provides services to others
A model where devices communicate directly
A model where data is stored locally on each device
What is peer-to-peer (P2P) networking and how does it differ from client-server?
P2P has centralized control; client-server does not
P2P has no central server; client-server does
P2P uses encryption; client-server does not
P2P is faster than client-server
A messaging app stores all messages on company servers. Another app sends messages directly between users' phones. Which model does each use?
Client-server and peer-to-peer
Peer-to-peer and client-server
Centralized and decentralized
Encrypted and unencrypted
A small office has all computers connected to a central switch. What topology is this?
Star topology
Ring topology
Bus topology
Mesh topology
A company's network continues functioning when one cable fails because traffic automatically uses another path. What characteristic of the network enables this?
Redundancy
Scalability
Latency
Bandwidth
What is the difference between a LAN and a WAN?
LAN covers a small geographic area, while WAN covers a large geographic area.
LAN is slower than WAN.
WAN is used only for wireless networks.
LAN requires more infrastructure than WAN.
A university has networks in multiple buildings connected together. All buildings are on the same campus. Is this a LAN or WAN?
LAN
WAN
MAN
PAN
What is a MAN (Metropolitan Area Network)?
A network that connects devices within a single room.
A network that connects devices across a city.
A network that connects devices across multiple countries.
A network that connects devices within a single building.
A home network has a laptop, smartphone, smart TV, printer, and a gaming console all connected to the router. What term describes the exponential growth of such connected devices?
Internet of Things (IoT)
Network Scalability
Redundancy
Bandwidth Expansion
What is a MAC address?
A unique identifier assigned to a network interface card.
A protocol used for routing data packets.
A type of IP address.
A device used to connect networks.
A network card has MAC address 00:1A:2B:3C:4D:5E. What do the first three pairs (00:1A:2B) represent?
Manufacturer of the network card.
Device type.
Network protocol.
IP address.
Why do devices need both MAC addresses and IP addresses?
MAC addresses identify devices on the local network, while IP addresses identify devices globally.
MAC addresses are used for wireless networks, while IP addresses are used for wired networks.
MAC addresses are temporary, while IP addresses are permanent.
MAC addresses are used for routing, while IP addresses are used for switching.
What is an Ethernet frame?
A data packet used in Ethernet networks.
A physical cable used for Ethernet connections.
A protocol for wireless communication.
A type of IP address.
A computer receives an Ethernet frame. The FCS check fails. What does the computer do?
Discards the frame.
Resends the frame.
Corrects the error and processes the frame.
Ignores the error and processes the frame.
Why do small ISPs pay larger ISPs for Internet connectivity?
To access a larger customer base
To connect to the global Internet
To improve their network speed
To reduce their operational costs
What is an IXP (Internet Exchange Point)?
A location where ISPs exchange traffic
A type of Internet protocol
A server used for storing data
A method for encrypting Internet traffic
What is a CDN (Content Delivery Network)?
A network for delivering emails
A system for storing and delivering web content
A protocol for Internet communication
A type of Internet service provider
Why do popular websites like YouTube and Netflix use CDNs?
To reduce server costs
To improve content delivery speed and reliability
To increase their advertising revenue
To store user data securely
What type of content is typically stored on CDN servers?
Dynamic web pages
Static content like images and videos
Encrypted user data
Real-time communication data
