Computer Communication Networks

Questions and Answers

What term is used to describe the sequence of packet switches and communication links in a computer network?

Topology

Protocol

Domain

Route (correct)

Which of the following best describes 'hosts' in a computer network?

Only servers that manage network traffic

Hardware components for communication

Devices that only send data

Systems running applications that generate or receive data (correct)

What is the primary purpose of the internet as described in the content?

To interconnect billions of computing devices providing services to applications (correct)

To serve as a platform for online gaming

To enable the sharing of single-user applications

To connect users for social media interaction

Which organization is NOT mentioned as part of the history of the internet?

Google Signup and view all the answers

What type of networks are included as examples of computer networks?

Home networks, enterprise networks, and mobile networks Signup and view all the answers

What makes applications categorized as distributed?

They operate independently on different hosts. Signup and view all the answers

What role do protocols play in network communication?

They define the format and order of messages exchanged. Signup and view all the answers

Which of the following describes the network edge?

It encompasses the access network and end-systems. Signup and view all the answers

What is the purpose of services provided by hardware or software in a network?

To offer reliability and guaranteed rates. Signup and view all the answers

Which classification of networks is based on their physical form?

Tree, star, ring, bus, and point-to-point topologies. Signup and view all the answers

Who is responsible for maintaining the TLD servers for the edu top-level domain?

Educause Signup and view all the answers

What type of records do authoritative DNS servers maintain?

Various DNS records corresponding to registered hosts Signup and view all the answers

What is the role of local DNS servers?

They query the DNS hierarchy on behalf of clients Signup and view all the answers

Which of the following services is NOT provided by the Domain Name System?

Securing domain registrations Signup and view all the answers

What does the 'TTL' in a resource record stand for?

Time To Live Signup and view all the answers

Which type of resource record maps a hostname to an IP address?

A Signup and view all the answers

Which record type specifies the canonical mail server name?

MX Signup and view all the answers

What is the function of an NS record in the Domain Name System?

Identifies the authoritative DNS server for a domain Signup and view all the answers

What is the role of a web cache when an object is not present?

It fetches the object from the Origin server and stores it. Signup and view all the answers

Why do users prefer using hostnames instead of IP addresses?

Hostnames are easier to remember than IP addresses. Signup and view all the answers

What transport layer protocol does DNS primarily use?

UDP Signup and view all the answers

What happens after the DNS server sends a DNS reply to a client?

A TCP handshake resumes using the provided IP address. Signup and view all the answers

What port does the DNS service operate on?

53 Signup and view all the answers

In what order does the encapsulation process occur during the DNS query?

DNS query encapsulated in UDP segment, followed by DNS reply. Signup and view all the answers

What does the DNS server do after it performs decapsulation of a DNS query?

It generates a DNS reply with the IP address of the web server. Signup and view all the answers

What is a unique characteristic of how each application chooses a source port number in Host A?

It randomly selects a new port number for each application. Signup and view all the answers

What is the primary function of SMTP in email transmission?

It sends messages from the sender to the recipient's mailbox. Signup and view all the answers

Which of the following statements accurately compares SMTP and HTTP?

SMTP does not support encoding formats other than ASCII. Signup and view all the answers

What port number is assigned for SMTP communications?

25 Signup and view all the answers

What is the major difference in behavior between SMTP and HTTP?

SMTP pushes data, while HTTP pulls data. Signup and view all the answers

What does RFC 5321 define?

The Simple Mail Transfer Protocol (SMTP). Signup and view all the answers

Study Notes

Introduction to Computer Networks

A computer network consists of end-systems (hosts) connected via communication links and packet switches.
Hosts generate or receive data as packets, and the route connecting these components is termed a path.
Administered by a single entity, networks include home, enterprise, and mobile networks.
Internet access for hosts is typically provided via Internet Service Providers (ISPs).

Overview of the Internet

The Internet connects billions of devices globally and serves as an architecture for distributed applications.
Originated from DARPA's ARPANET with developments in packet-switched networks, TCP/IP protocols, and key services like DNS and IANA.
Key entities in Internet governance include ICANN, RFC, IETF, IESG, and IAB.

Internet Visualization

The Internet is depicted as a graphical network facilitating distributed applications.
End systems, known as hosts, reside at the network's edge.
Hosts exchange messages using internet socket interfaces; protocols dictate message format, order, and associated actions.

Network Classification

End-systems are categorized as clients (requesting services) and servers (providing services).
Gateways connect access networks to ISPs.
Access networks vary by size (LAN, home networks, WAN) and topology (tree, star, ring, bus).

Web and HTTP Caching

Web caching optimizes content delivery: if an object is cached, it is fetched directly; if not, a connection is made to the origin server to retrieve and store it.

Domain Name System (DNS)

DNS, specified in RFC 1034 and 1035, translates hostnames to IP addresses (e.g., gaia.cs.umass.edu translates to 128.119.245.12).
The system utilizes a distributed architecture of DNS servers, primarily using UDP and operating on port 53.
Local DNS servers act as proxies within access networks, querying the DNS hierarchy on behalf of clients.

DNS Functionality and Services

DNS provides various services: IP address resolution for hostnames, host aliasing, mail server aliasing, and load distribution.
Resource records are queried by type, name, and value; common record types include A (IP addresses), NS (authoritative DNS), CNAME (canonical hostname), and MX (mail exchange).

Electronic Mail and SMTP

SMTP, detailed in RFC 5321, is a core email protocol older than HTTP, utilizing ASCII encoding for message transport.
SMTP operates in a "push" manner, sending messages from servers, while HTTP functions as a "pull" protocol.
TCP connections facilitate email transmission between sender's and recipient's mail servers, operating on socket number 25.

Video Streaming Trends

On-demand video streaming constitutes approximately 80% of internet traffic, according to CISCO's 2020 annual report.
Leading video streaming services include Netflix, Hotstar, Amazon Prime, and YouTube.

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Description

This quiz covers the fundamental principles of computer communications networks, focusing on internet architecture and applications. Explore the concepts of network organization, communication links, and the role of hosts in a networked environment. Perfect for students in Electronics and Communication Engineering.

Computer Communication Networks - Unit 1