Advanced Networking
What are the consequences of finite queue capacity in a network node with regard to packet handling?
A router will drop packets if the queue is full, leading to packet loss. Packet loss increases as the traffic intensity increases. End-systems perceive packet loss as packets disappearing into the network core. Finite queue capacity can lead to overflow and packet loss, as seen in the Java applet for a queue.
What is a Web cache?
A server that satisfies HTTP requests on behalf of an origin Web server.
What is a socket ? (Select all that apply)
A software interface between the application and network A logical connection between two hosts
What is a socket? (Select all that apply)
A software interface between the application and network A logical connection between two hosts
What is a socket ? (Select all that apply)
A software interface between the application and network Negotiating and synchronizing TCP parameters
What is a Web cache ? (Select all that apply)
A storage mechanism for temporarily storing web content A server that stores previously accessed web pages for faster retrieval A component that reduces network traffic and improves performance
What are characteristics and concepts related to the interconnection of access ISPs in the context of the Internet's network structure?
Access ISPs can be universities or companies, not limited to traditional telecommunications providers. The interconnection of access ISPs is crucial for connecting the billions of end systems on the Internet. A global transit ISP is a provider, and an access ISP is a customer in terms of connectivity.
What is the purpose of load distribution in DNS ? (Select all that apply)
Balancing the network traffic across multiple servers or resources Enhancing the fault tolerance and resilience of the system Reducing latency and improving response times for clients Facilitating efficient utilization of server resources
Which of the following is an example of a proprietary application-layer protocol? (Select all that apply)
BitTorrent Skype
How do time-sensitive applications cope with the lack of timing and throughput guarantees provided by today's Internet transport protocols? (Select all that apply)
By implementing their own timing and throughput control mechanisms By relying on specialized real-time transport protocols By utilizing quality-of-service (QoS) mechanisms and network prioritization By adjusting the application behavior based on observed network conditions
How can Web caching reduce traffic on an institution's access link to the Internet ? (Select all that apply)
By reducing the number of HTTP request messages sent. By serving cached web content directly to the clients within the institution
How do time-sensitive applications cope with the lack of timing and throughput guarantees provided by today's Internet transport protocols ? (Select all that apply)
By relying on clever design By adjusting the application behavior based on observed network conditions
How can Web caching reduce traffic on an institution's access link to the Internet? (Select all that apply)
By serving cached web content directly to the clients within the institution By reducing the number of requests sent to external servers for the same content By storing frequently accessed web content locally in the institution's cache
How does the transport layer implement the demultiplexing service? (Select all that apply)
By using the source port number By using the destination port number
What is the purpose of a local DNS server ? (Select all that apply)
Caching frequently accessed DNS information for faster query resolution Providing DNS resolution services to local network clients Managing and resolving internal domain names within a private network
What control does an application developer have on the transport-layer side of a socket? (Select all that apply)
Choosing the transport protocol (e.g., TCP, UDP) Correct! Specifying the source and destination ports Correct! Configuring socket options (e.g., timeout, buffer size) Correct! Implementing error handling and recovery mechanisms
In the given example, why is packet switching considered more efficient for sharing a 1 Mbps link among users with alternating activity and inactivity?
Circuit switching would require reserving 100 kbps for each user regardless of their activity. Packet switching allows users to dynamically share the link's capacity during their active periods.
What are characteristics of circuit-switched networks based on the provided information?
Circuit-switched networks reserve dedicated resources for the entire duration of a connection. Each link in a circuit-switched network has multiple circuits to support simultaneous connections. Dedicated end-to-end connections are established between hosts in circuit-switched networks. The transmission capacity of each end-to-end circuit-switched connection is fixed and guaranteed.
What are the key differences between circuit-switched and packet-switched networks based on the provided information?
Circuit-switched networks reserve resources for the entire duration of a communication session. In circuit-switched networks, resources are used on-demand and may involve queuing. Circuit-switched networks are analogous to restaurants that require reservations.
Which statements about coaxial cable and optical fiber as transmission media are true based on the information provided in the Book?
Coaxial cable is commonly used in cable television systems and can achieve high data transmission rates. In cable television and cable Internet access, coaxial cable is a guided shared medium where multiple end systems can directly connect to it. The Optical Carrier (OC) standard link speeds for optical fiber range from 51.8 Mbps to 39.8 Gbps.
Which of the following is NOT defined by an application-layer protocol? (Select all that apply)
Communication port numbers Network routing and addressing
What control does an application developer have on the transport-layer side of a socket ?
Configuring socket options (e.g., timeout, buffer size) Limited control of transport-layer parameters
What type of connection does TCP establish between the two processes ? (Select all that apply)
Connection-oriented Reliable Full-duplex
Which of the following services is provided by TCP? (Select all that apply)
Connection-oriented communication Reliable data delivery Flow control Congestion control
What distinguishes Network Structure 5 from Network Structure 4 as described in the Book?
Content provider networks in Network Structure 5 have their private networks separate from the public Internet. Network Structure 5 adds content provider networks, such as Google, to the Internet ecosystem.
Which of the following is an example of an application-layer protocol that defines the format and sequence of messages exchanged between a Netflix server and client? (Select all that apply)
DASH
What is the purpose of an application-layer protocol? (Select all that apply)
Defining the format and structure of application-layer messages Facilitating communication between applications on different hosts Enabling data exchange and interaction between applications
What factors contribute to measuring the performance of a computer network node?
Delay Packet loss probability End-to-end throughput Instantaneous throughput
How does packet forwarding work in the Internet based on the provided information?
Each router has a forwarding table mapping destination addresses to outbound links. Packets include the destination's IP address in their headers. Routers forward packets based on a hierarchical structure of the destination address. Gas station attendants and kids on bicycles represent routers in the packet forwarding process.
How does TCP ensure reliable data transfer ? (Select all that apply)
Error detection and error correction techniques By delivering all data sent without error and in the proper order
What is a socket's role in the message transmission process ? (Select all that apply)
Establishing a network connection Correct! Providing a reliable communication channel Correct! Encoding and decoding data
What is a socket's role in the message transmission process ? (Select all that apply)
Establishing a network connection Providing a reliable communication channel Encoding and decoding data
What is a socket's role in the message transmission process? (Select all that apply)
Establishing a network connection To provide a software interface between the application and the network
What is the purpose of the handshaking procedure in TCP ? (Select all that apply)
Establishing a reliable connection between two hosts Exchanging initial sequence numbers for reliable data transfer Negotiating and synchronizing TCP parameters
What type of connection does TCP establish between the two processes? (Select all that apply)
Full-duplex Reliable
What are some possible values of the method field in an HTTP request message ? (Select all that apply)
GET, POST, HEAD, PUT, and DELETE
Analogously, in the given car journey analogy, which elements correspond to routers and their functions in the packet forwarding process?
Gas station attendants represent routers that determine the next hop for the packet. Interstate highways (e.g., I-95, I-4) correspond to communication links. Extracting address portions (e.g., Florida, Orlando) corresponds to looking up forwarding tables.
Which of the following statements about communication satellites are true based on the information provided in the Book?
Geostationary satellites remain permanently above the same spot on Earth. Geostationary satellites are placed in orbit at 36,000 kilometers above Earth's surface. LEO satellites rotate around Earth and do not remain permanently above one spot.
Why do routers prefer fixed-length, hierarchically structured IP addresses over hostnames? (Select all that apply)
IP addresses are more efficient for routing purposes Hierarchically structured IP addresses enable hierarchical routing and scalability.
What is the purpose of the request line in an HTTP request message? (Select all that apply)
Identifying the target resource or URL Correct! Specifying the HTTP version being used Correct! Indicating the desired action or method (e.g., GET, POST)
What distinguishes packet-switched networks from circuit-switched networks based on the provided information?
In packet-switched networks, packets are sent without reserving link resources. Packet-switched networks may involve packet queuing and delays.
How does a Web cache respond to an HTTP request for an object? (Select all that apply)
It checks if the requested object is already in its cache. If the object is in the cache and is fresh, it directly serves the object to the client. If the object is in the cache but has expired, it sends a conditional request to the origin server to check for an updated version. If the object is not in the cache, it forwards the request to the origin server to fetch the object and then stores it in the cache for future requests.
What is the disadvantage of using UDP for data transfer? (Select all that apply)
It provides no guarantee that the message will ever reach the receiving process Inability to handle congestion control
What is the main disadvantage of UDP? (Select all that apply)
Lack of reliability and error recovery mechanisms Correct! No guarantee of packet delivery or order of arrival Correct Answer Limited support for large data payloads Correct! Inability to handle congestion control
What is the disadvantage of using UDP for data transfer ? (Select all that apply)
Lack of reliability and error recovery mechanisms No guarantee of packet delivery or order of arrival Higher overhead due to additional headers Inability to handle congestion control
What control does an application developer have on the transport-layer side of a socket ? (Select all that apply)
Limited control of transport-layer parameters Configuring socket options (e.g., timeout, buffer size)
What is the problem with a centralized DNS design? (Select all that apply)
Limited scalability A single DNS server would be a single point of failure.
Which transport protocol provides security services by default? (Select all that apply)
Neither TCP nor UDP Correct! TLS
Who typically installs and configures a Web cache? (Select all that apply)
Network administrators Answer Web server administrators Internet service providers (ISPs) Content delivery network (CDN) providers
Which of the following is NOT defined by an application-layer protocol ? (Select all that apply)
Network routing and addressing Physical characteristics of network cables.
Can today's Internet transport protocols provide timing and throughput guarantees? (Select all that apply)
No Correct! It depends on the specific transport protocol being used.
Can today's Internet transport protocols provide timing and throughput guarantees ? (Select all that apply)
No, they cannot provide precise timing guarantees. No, they cannot provide guaranteed throughput rates. It depends on the specific transport protocol being used.
What are the types of delays that a packet may experience at a router node in a computer network as described in the Book?
Nodal processing delay Queueing delay
What is the default mode of HTTP in terms of using persistent or non-persistent connections? (Select all that apply)
Non-persistent connections It depends on the specific version of HTTP being used
What is the difference between non-persistent and persistent connections in client-server interaction over TCP? (Select all that apply)
Non-persistent connections use a separate TCP connection for each request/response pair, while persistent connections use the same TCP connection for multiple requests and responses
What role do output buffers play in packet switching?
Output buffers introduce store-and-forward delays in packet switching. Output buffers cause packet loss when they become completely full.
Which of the following best describes the store-and-forward transmission method used by most packet switches, including routers?
Packets are stored entirely before being forwarded. Before being forwarded, packets are completely saved.
In the given network scenario, what happens when the arrival rate of packets to the router exceeds the capacity of the 1.5 Mbps link?
Packets experience queuing delays in the link's output buffer. The router's output buffer becomes congested. Congestion occurs, similar to waiting in line at a bank teller or tollbooth.
What are the components and characteristics of Network Structure 4 as described in the Book?
Peering between two ISPs typically involves a settlement-free arrangement where neither ISP pays the other. Internet Exchange Points (IXPs) serve as meeting points where multiple ISPs can peer together. In Network Structure 4, content provider networks are interconnected with access ISPs. Network Structure 4 includes access ISPs, regional ISPs, tier-1 ISPs, PoPs, multi-homing, peering, and IXPs.
Which of the following statements about radio channels and their characteristics are true based on the information provided in the Book?
Radio channels can penetrate walls and provide connectivity to mobile users. Multipath fading is caused by signal reflection off of interfering objects. Terrestrial radio channels can be classified into three groups based on their operating distance.
What are the characteristics and components of the hierarchical network structure of the Internet as described in the Book?
Regional ISPs connect to multiple access ISPs within a region. Points of presence (PoPs) are present at all levels of the hierarchy except the access ISP level.
What is the main difference between TCP and UDP? (Select all that apply)
Reliability of data transfer Correct! Connection-oriented vs connectionless Correct! Packet ordering guarantee Correct! Congestion control mechanisms Correct! Overhead and efficiency
Which of the following services is provided by TCP ? (Select all that apply)
Reliable end-to-end data transfer Correct! Flow control
What is the function of TLD servers in the DNS hierarchy ? (Select all that apply)
Resolving queries for specific top-level domains (TLDs) Providing referrals to authoritative DNS servers for second-level domains Maintaining a global database of all registered domain names
What is the function of root DNS servers in the DNS hierarchy ? (Select all that apply)
Resolving top-level domain (TLD) queries Providing referrals to authoritative DNS servers for specific domains Maintaining a global database of all registered domain names
How does TCP ensure reliable data transfer? (Select all that apply)
Sequence numbering and acknowledgement mechanism Correct! Flow control and congestion control mechanisms Correct! Retransmission of lost or corrupted packets Correct! Error detection and error correction techniques
How does TCP ensure reliable data transfer? (Select all that apply)
Sequence numbering and acknowledgement mechanism Flow control and congestion control mechanisms Retransmission of lost or corrupted packets Error detection and error correction techniques
What is the problem with a centralized DNS design ? (Select all that apply)
Single point of failure Limited scalability Lack of redundancy
What is the function of authoritative DNS servers in the DNS hierarchy ? (Select all that apply)
Storing and managing DNS records for specific domains Responding with authoritative information about a domain's DNS records
What is the main difference between TCP and UDP ? (Select all that apply)
TCP provides a reliable data transfer service, while UDP provides an unreliable data transfer service Overhead and efficiency
Which of the following are examples of unguided media for transmitting data in computer networks, as mentioned in the Book?
Terrestrial radio spectrum Satellite radio spectrum
What is the purpose of the handshaking procedure in TCP? (Select all that apply)
To alert the client and server and prepare them for data transfer Negotiating and synchronizing TCP parameters
What is the purpose of a Web cache?
To decrease the response time for a client request.
What is the purpose of an application-layer protocol ? (Select all that apply)
To define how an application's processes pass messages to each other. Enabling data exchange and interaction between applications
What is the purpose of the HTTP application-layer protocol? (Select all that apply)
To define how users obtain documents from Web servers on demand. Supporting client-server interaction and request-response model
What is the primary function of breaking long messages into smaller packets in a network application?
To facilitate efficient transmission over communication links. To enable effective communication across communication networks
What is the purpose of using cookies in HTTP ?
To keep track of users on a website
What is the purpose of a local DNS server? (Select all that apply)
To provide a DNS server that is "close to" the client. Providing DNS resolution services to local network clients
What is the main task of the domain name system (DNS) ? (Select all that apply)
To translate hostnames to IP addresses Translating domain names into IP addresses
What is the purpose of using cookies in HTTP? (Select all that apply)
Tracking and maintaining session state between client and server Correct! Storing user preferences and personalized settings Correct! Implementing user authentication and authorization mechanisms
What is the purpose of the HTTP application-layer protocol ? (Select all that apply)
Transferring hypertext documents over the Internet Enabling communication between web browsers and web servers Supporting client-server interaction and request-response model
Which of the following are examples of guided media for transmitting data in computer networks, as mentioned in the Book?
Twisted-pair copper wire Coaxial cable Multimode fiber-optic cable
Which statements about twisted-pair copper wire as a transmission medium are true based on the information provided in the Book?
Twisted-pair copper wire has been used by telephone networks for over a hundred years. Twisted-pair copper wire is commonly used for LANs within a building. Twisted pair technology can achieve data rates of up to 10 Gbps for distances up to a hundred meters.
What is the main disadvantage of UDP ? (Select all that apply)
Unreliable data transfer Limited support for large data payloads
What does the traffic intensity (La/R) indicate in the context of queuing delay in a computer network as described in the Book?
When La/R > 1, it means the queuing delay will approach infinity. When La/R ≤ 1, it means the average queuing delay can vary depending on the nature of arriving traffic.
What factors affect the average queuing delay in a computer network, particularly when packet arrivals are random?
The traffic intensity (La/R), where La is the rate of packet arrivals and R is the transmission rate. Variations in packet arrival rate.
How is the transmission rate of a circuit calculated in TDM based on the provided information?
The transmission rate is determined by the number of bits in a time slot. The transmission rate is equal to the frame rate multiplied by the number of bits in a slot.
What is the function of authoritative DNS servers in the DNS hierarchy? (Select all that apply)
They maintain the DNS records for all Internet hosts. Storing and managing DNS records for specific domains
What is the function of TLD servers in the DNS hierarchy? (Select all that apply)
They provide the IP addresses for authoritative DNS servers. Maintaining a global database of all registered domain names
What is true about the customer-provider relationships in the hierarchical network structure of the Internet as described in the Book?
Tier-1 ISPs do not have customer-provider relationships as they are at the top of the hierarchy. Access ISPs pay the regional ISPs they connect to, and regional ISPs pay the tier-1 ISPs they connect to. In some regions, larger regional ISPs may exist, connecting to smaller regional ISPs before reaching tier-1 ISPs.
What factors contribute to the nodal processing delay and queuing delay experienced by a packet at a router in a computer network as described in the Book?
The time needed to check for bit-level errors in the packet's header. The number of earlier-arriving packets waiting for transmission in the queue. The intensity and nature of the traffic arriving at the queue.
What factors contribute to the total nodal delay experienced by a packet at a router in a computer network as described in the Book?
The length of the packet (L bits). The transmission rate of the link from router A to router B (R bits/sec). The propagation speed of the link.The distance between router A and router B.
What are factors that can affect the queuing delay in a computer network as described in the Book?
The nature of the arriving traffic, such as whether it arrives periodically or in bursts. The rate at which packets arrive at the queue (a). The transmission rate of the link (R).
What are factors that can affect the queuing delay in a computer network as described in the Book?
The rate at which packets arrive at the queue (a). The transmission rate of the link (R). The nature of the arriving traffic, such as whether it arrives periodically or in bursts.
