Data Communication & Networking (QUESTION BANK)
(CSE) Question and answer
UNIT-6
1 What is client servr paradigm?describe in detail
2 Explain Application Programming Interface(API)
3 Explain flow diagram for iterative UDP communication
4 WHAT IS HTTP ? explain Non persistent and persistent protocol
5 What is proxy server? Explain in detail
6 What is FTP? explain types of connection
7 Explain Data security connection of FTP
8 Explain Email Architecture
9 Explain 1. POP3 2. IMAP 3. MIME
10 What is DNS? Explain its purpose
11 Explain Domain Name space
12 What is SNMP? Explain its management components
13 What is MIB? Explain its objects
14 What is ASN.1? Explain its symbol with its meaning
15 What is SMi? Explain in details
16 Explain Hierarchy of name srvers
17 Explain different type of domains
(NOTE: EXPLORE THIS QUESTIONS ACCORDING TO YOUR NEED)
1. What is the client-server paradigm? Describe in detail.
The client-server paradigm is a model for designing and implementing distributed computing systems. In this paradigm, there are two main components: the client and the server. The client is a program or device that requests services or resources from the server, while the server is a program or device that provides these services or resources.
The communication between the client and server follows a specific pattern. The client initiates a request to the server, specifying the desired service or resource. The server receives the request, processes it, and sends back a response containing the requested data or an acknowledgment of the completed action.
The client-server paradigm offers several advantages. It allows for a division of labor, with servers specializing in providing specific services, such as file storage, database management, or web hosting. Clients can be lightweight devices, such as smartphones or laptops, as they rely on the server's resources. This model also enables scalability, as multiple clients can simultaneously connect to a server, and additional servers can be added to handle increased demand.
2. Explain Application Programming Interface (API).
An Application Programming Interface (API) is a set of rules and protocols that specifies how software components should interact with each other. It provides a defined interface through which different software systems can communicate and exchange information.
APIs define the methods, data structures, and protocols that developers can use to integrate their applications with external systems, libraries, or services. They establish a contract between the software components, allowing them to interact and exchange data in a standardized and predictable manner.
APIs can be classified into different types, such as web APIs, operating system APIs, or library APIs. Web APIs, often referred to as REST APIs or web services, enable communication between applications over the internet using standard protocols like HTTP. Operating system APIs provide a set of functions and services for interacting with the underlying operating system, while library APIs offer pre-built functions and modules for specific programming languages or frameworks.
3. Explain the flow diagram for iterative UDP communication.
In iterative UDP communication, a server listens for incoming datagrams on a specific port while handling client requests one at a time. The following flow diagram illustrates the iterative UDP communication process:
1. The server creates a socket and binds it to a specific port to listen for incoming datagrams.
2. The server enters a loop to wait for client requests.
3. When a client sends a datagram to the server's port, the server receives the datagram.
4. The server processes the received datagram, extracting the request from it.
5. The server performs the necessary operations to fulfill the client's request.
6. The server generates a response datagram containing the requested data or an acknowledgment.
7. The server sends the response datagram back to the client's IP address and port.
8. The server returns to the loop, waiting for the next client request.
This process repeats for each client request, with the server handling them sequentially. It's important to note that in iterative UDP communication, each client request is processed and completed before the server moves on to the next request.
4. What is HTTP? Explain non-persistent and persistent protocol.
HTTP (Hypertext Transfer Protocol) is a protocol used for transmitting data over the internet. It is the foundation of the World Wide Web and allows web browsers to communicate with web servers.
Non-persistent HTTP is a type of HTTP connection where a separate TCP connection is established for each request/response pair. In non-persistent HTTP, after the response is received, the TCP connection is closed. Subsequent requests require establishing a new TCP connection, incurring the overhead of connection setup and teardown for each request. Non-persistent HTTP is simple to implement but can be less efficient due to the repeated connection establishment overhead.
Persistent HTTP, also
known as HTTP keep-alive or HTTP persistent connection, allows multiple requests and responses to be sent over a single TCP connection. After a request is made and a response is received, the connection remains open, and subsequent requests can be sent without the need for establishing a new connection each time. Persistent HTTP reduces the overhead of connection establishment, improves response time, and enables efficient use of network resources.
5. What is a proxy server? Explain in detail.
A proxy server is an intermediary server that sits between a client and a destination server. When a client sends a request to access a resource, the request is first routed to the proxy server, which then forwards the request to the destination server on behalf of the client. The proxy server acts as a gateway or middleman, facilitating communication between the client and the server.
The primary purposes of a proxy server include:
- Caching: Proxy servers can store copies of requested resources locally. When a client makes a subsequent request for the same resource, the proxy can deliver it directly, reducing latency and bandwidth usage.
- Anonymity: Proxy servers can mask the client's IP address, providing anonymity and privacy for the client.
- Filtering: Proxy servers can be configured to filter and block certain requests based on predefined rules. This allows organizations to restrict access to specific websites or content.
- Load balancing: Proxy servers can distribute incoming client requests across multiple servers to balance the load and improve performance.
- Security: Proxy servers can act as a firewall by inspecting and filtering incoming and outgoing traffic, providing an additional layer of security.
Overall, proxy servers provide various benefits such as improved performance, enhanced security, and control over network resources by acting as an intermediary between clients and servers.
6. What is FTP? Explain types of connection.
FTP (File Transfer Protocol) is a standard network protocol used for transferring files between a client and a server on a computer network. It provides a simple and reliable method for file sharing and management.
There are two types of connections in FTP:
a) Active FTP: In active FTP, the client initiates the connection to the server. The client sends a command to the server to establish a connection for data transfer. The server then opens a separate port and listens for incoming data connections from the client. The client sends data through this connection while the server receives it. Active FTP requires the server to have the ability to accept incoming connections.
b) Passive FTP: In passive FTP, the server initiates the connection to the client. The client sends a command to the server requesting a passive mode connection. The server responds with an IP address and port number where the client should connect. The client then establishes a connection to the server's specified IP address and port. The server sends data through this connection while the client receives it. Passive FTP is commonly used in situations where the client is behind a firewall or NAT (Network Address Translation) device that prevents incoming connections.
The choice between active and passive FTP depends on the network configuration and any firewall or NAT restrictions in place. Active FTP may encounter issues when the client is behind a firewall, as the incoming data connection from the server may be blocked. In such cases, passive FTP is typically used.
7. Explain the data security connection of FTP.
FTP does not provide built-in encryption, so the data transferred over FTP connections is not inherently secure. However, there are additional measures that can be taken to secure the FTP connection:
a) FTPS (FTP Secure): FTPS is an extension of FTP that adds support for Transport Layer Security (TLS) or Secure Sockets Layer (SSL) encryption. It provides secure communication between the client and the server by encrypting the data and ensuring its integrity. FTPS requires the use of digital certificates to authenticate the server and, optionally, the client.
b) SFTP (SSH File Transfer Protocol): SFTP is not related to FTP but provides similar file transfer capabilities over a secure SSH (Secure Shell) connection. It uses the SSH protocol to establish an encrypted connection and authenticate the client and server. SFTP provides secure file transfer and remote file management.
By using FTPS or SFTP, the data transmitted over the FTP connection can be encrypted, protecting it from unauthorized access or interception.
8. Explain Email Architecture.
Email architecture refers to the system and protocols involved in the exchange and delivery of email messages. The architecture comprises various components that work together to enable email communication. Here are the main components of email architecture:
a) User Agent (UA): A user agent, commonly known as an email client, is a software application that allows users to compose, send, receive, and manage email messages. Examples of email clients include Outlook, Gmail, and Thunderbird. The user agent interacts with other components to send and receive emails.
b) Mail Transfer Agent (MTA): The mail transfer agent, also known as the mail server, is responsible for the transmission of email messages between different systems. When a user sends an email, the user agent contacts the outgoing mail server, which then routes the message to the appropriate destination server. The destination server may be another MTA or a mailbox server.
c) Mailbox Server: The mailbox server stores and manages email messages on behalf of the users. It holds the incoming messages until the user retrieves them through their user agent. The mailbox server is responsible for message storage, retrieval, and organization.
d) Message Transfer Agent (MTA): The message transfer agent is a component that handles the routing and delivery of email messages within a specific domain. It works within an organization's network and is responsible for exchanging emails between the sender and recipient's mailbox servers.
e) Domain Name System (DNS): DNS plays a vital role in email architecture. It resolves domain names to IP addresses, allowing the mail transfer agents to identify the destination server for email delivery.
The overall process of sending and receiving emails involves the user agent composing and sending the email, which is then transferred through the appropriate mail transfer agents until it reaches the recipient's mailbox server. The recipient's user agent retrieves the email from the server for the user to read.
9. Explain:POP3 , IMAP, MIME
1. POP3 (Post Office Protocol version 3): POP3 is an email retrieval protocol used by email clients to retrieve email messages from a remote server. It operates by downloading emails from the server to the client device and deleting them from the server unless configured otherwise. POP3 is suitable for users who prefer to store and manage their emails locally.
2. IMAP (Internet Message Access Protocol): IMAP is another email retrieval protocol that allows email clients to access and manage email messages stored on a remote server. Unlike POP3, IMAP retains copies of emails on the server, allowing users to access their emails from multiple devices. IMAP provides advanced features such as folder management, searching, and synchronizing changes across devices.
3. MIME (Multipurpose Internet Mail Extensions): MIME is a standard that extends the capabilities of email messages beyond plain text. It enables the inclusion of various content types, including attachments, images, audio, and video, within email messages. MIME defines the structure and encoding methods for these non-textual components, allowing them to be transmitted and displayed correctly by email clients.
10. What is DNS? Explain its purpose.
DNS (Domain Name System) is a distributed hierarchical system that translates domain names into IP addresses. It serves as a directory for the internet, mapping user-friendly domain names (e.g., www.example.com) to the corresponding IP addresses (e.g., 192.0.2.1) that computers use to identify and communicate with each other.
The purpose of DNS is twofold:
a) Domain Name Resolution: DNS enables the resolution of domain names to IP addresses. When a user enters a domain name in a web browser or sends an email, the DNS system translates the domain name into the associated IP address. This allows the user's device to establish a connection with the appropriate server for the requested service.
b) Load Distribution and Redundancy: DNS can distribute the
load among multiple servers to enhance performance and scalability. By configuring multiple IP addresses for a single domain name, DNS can rotate the responses it provides, spreading the incoming traffic across different servers. DNS can also provide redundancy by automatically redirecting requests to alternate servers if one becomes unavailable.
Overall, DNS plays a critical role in enabling the human-readable domain names we use to navigate the internet and ensuring the efficient and reliable routing of internet traffic.
11. Explain Domain Name Space.
Domain Name Space refers to the hierarchical structure of domain names on the internet. It organizes domain names into a tree-like structure, with the root at the top and subsequent levels branching out beneath it. Each level represents a specific domain, such as top-level domains (TLDs), second-level domains (SLDs), and subdomains.
The Domain Name Space follows the Domain Name System (DNS) hierarchy. The highest level is the root domain, denoted by a single dot ".", which is the starting point of the tree. Below the root, there are several top-level domains (TLDs), such as .com, .org, .net, .gov, and country-specific TLDs like .uk, .fr, and .jp.
Beneath the TLDs are the second-level domains (SLDs). These are typically registered by organizations or individuals and form the main part of a website's address. For example, in the domain name "example.com," the SLD is "example."
Subdomains are created by adding additional levels to the domain name. They allow further categorization or organization of websites. For instance, "blog.example.com" is a subdomain of "example.com," indicating that it is specifically designated for blog content.
The hierarchical structure of the Domain Name Space ensures uniqueness and provides a systematic way of organizing and identifying websites and resources on the internet. DNS servers maintain and distribute information about domain names and their corresponding IP addresses, allowing users to access websites by simply typing in the domain name.
12. What is SNMP? Explain its management components.
SNMP (Simple Network Management Protocol) is an application-layer protocol used for managing and monitoring network devices and systems. It allows network administrators to gather information, monitor performance, and control network devices from a central management station.
SNMP consists of three primary management components:
a) Managed Devices: Managed devices are network devices, such as routers, switches, servers, printers, and sensors, that are monitored and controlled using SNMP. These devices contain SNMP agents, which are software modules responsible for collecting and reporting information to the SNMP manager.
b) SNMP Managers: SNMP managers are software applications or systems that serve as the central control point for managing network devices. They send SNMP requests to managed devices to retrieve information or issue commands. SNMP managers receive and process the information provided by SNMP agents.
c) SNMP Agents: SNMP agents are software modules embedded in managed devices. They collect and store management information about the device, including network statistics, performance metrics, and configuration details. SNMP agents respond to SNMP manager requests, providing the requested information or performing actions based on the manager's instructions.
The SNMP manager communicates with SNMP agents using a set of standardized operations and data structures defined by SNMP. It can retrieve information (GET operation), set configuration parameters (SET operation), receive event notifications (TRAP operation), and perform other management tasks.
SNMP is widely used for network management, enabling administrators to monitor and control network devices remotely, track performance, troubleshoot issues, and ensure optimal network operation.
13. What is MIB? Explain its objects.
MIB (Management Information Base) is a database or collection of variables that define the management information for a particular network device. It organizes and structures the information that can be managed and monitored using SNMP.
MIB consists of managed objects, which are individual variables or parameters that represent specific attributes or characteristics of a network device. Each managed object is identified by an Object Identifier (OID), which provides a unique address within the MIB hierarchy.
Managed objects in MIB can represent various aspects of a network device, including hardware information, configuration settings, performance metrics, and operational states. Examples of managed objects include interface status, CPU utilization, memory usage, routing tables, and
error counters.
The structure and organization of MIB follow a hierarchical tree-like structure. The top-level of the MIB hierarchy is called the root, and beneath it, different branches represent different groups or categories of managed objects. The structure of MIB is defined using a language called the Structure of Management Information (SMI).
SNMP managers use the MIB to navigate and retrieve specific information from managed devices. They can query the MIB using the Object Identifier (OID) of a particular managed object to retrieve its value or modify its configuration.
MIB plays a crucial role in SNMP-based network management by providing a standardized framework for managing and monitoring network devices, ensuring interoperability between SNMP managers and managed devices.
14. What is ASN.1? Explain its symbols with their meanings.
ASN.1 (Abstract Syntax Notation One) is a standard notation used to describe the structure and encoding of data for communication protocols, including SNMP. It provides a language-independent and platform-independent way of specifying data formats.
ASN.1 uses symbols to define data types and structures. Here are some commonly used symbols in ASN.1 and their meanings:
a) MODULE: The MODULE keyword is used to define a module, which is a collection of related ASN.1 definitions.
b) DEFINITIONS: The DEFINITIONS keyword is used to start the definition of ASN.1 types and structures within a module.
c) ::= (double colon equal sign): The double colon equal sign is used as an assignment operator in ASN.1. It assigns a name to a defined type or value.
d) SEQUENCE: The SEQUENCE keyword is used to define a sequence of components or fields within a data structure. Each component can have its own data type.
e) CHOICE: The CHOICE keyword is used to define a choice among several alternative components within a data structure. Only one component can be present in a choice at a time.
f) INTEGER: The INTEGER keyword is used to define a data type that represents integer values.
g) OCTET STRING: The OCTET STRING keyword is used to define a data type that represents a sequence of arbitrary bytes or octets.
h) OBJECT IDENTIFIER: The OBJECT IDENTIFIER keyword is used to define a data type that represents a globally unique identifier for objects or attributes.
i) BOOLEAN: The BOOLEAN keyword is used to define a data type that represents boolean values, i.e., true or false.
These symbols, along with other constructs and data types defined in ASN.1, allow for the precise specification of data formats and structures used in communication protocols.
15. What is SMi? Explain in detail.
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16. Explain the Hierarchy of Name Servers.
The hierarchy of name servers, also known as the DNS hierarchy, represents the organization and distribution of DNS servers responsible for resolving domain names into IP addresses. The DNS hierarchy follows a tree-like structure, with multiple levels of name servers.
At the top of the hierarchy is the root name server. There are 13 sets of root name servers distributed worldwide, each represented by a letter (A to M). These root name servers contain the authoritative information about the top-level domains (TLDs) and their associated name servers. When a DNS resolver receives a query for a domain, it starts by contacting one of the root name servers to obtain the information about the TLD name servers.
The next level in the hierarchy consists of TLD name servers. These name servers are responsible for storing the information about specific
top-level domains, such as .com, .org, .net, and country-specific TLDs like .uk, .fr, and .jp. TLD name servers maintain the information about the authoritative name servers for the second-level domains (SLDs) within their respective TLD.
Below the TLD name servers are the authoritative name servers for SLDs. These name servers store the DNS records (such as A records, MX records, and NS records) for individual domain names under their respective SLD. When a DNS resolver receives a query for a specific domain, it contacts the authoritative name server for that domain to retrieve the corresponding IP address or other records.
The hierarchy of name servers enables the distributed and efficient resolution of domain names. Each level of name servers caches the information obtained from higher-level servers, reducing the overall DNS query traffic and improving the response time for subsequent queries.
17. Explain different types of domains.
In the context of the internet, there are different types of domains that serve various purposes. Here are some common types of domains:
a) Top-Level Domains (TLDs): TLDs are the highest level of domains in the DNS hierarchy. They represent the most general categories of domain names. Examples of TLDs include .com, .org, .net, .edu, .gov, and country-specific TLDs like .uk, .fr, and .jp.
b) Second-Level Domains (SLDs): SLDs are the domains that appear directly to the left of the TLD in a domain name. They represent specific organizations, businesses, or individuals. For example, in the domain name "example.com," "example" is the SLD.
c) Country-Code Top-Level Domains (ccTLDs): ccTLDs are TLDs that represent specific countries or territories. They are typically two-letter codes assigned to each country or territory, such as .us for the United States, .uk for the United Kingdom, and .de for Germany.
d) Generic Top-Level Domains (gTLDs): gTLDs are TLDs that are not country-specific and are open for registration by entities worldwide. They include categories like .com, .org, .net, .info, .biz, and many others.
e) Sponsored Top-Level Domains (sTLDs): sTLDs are specialized TLDs that are sponsored by specific organizations or interest groups. They are intended for specific communities or industries. Examples of sTLDs include .gov (sponsored by the U.S. government), .edu (sponsored by educational institutions), and .mil (sponsored by the U.S. military).
f) Infrastructure Top-Level Domains (iTLDs): iTLDs are TLDs used for critical internet infrastructure and technical purposes. They are not available for general registration. Examples include .arpa (used for addressing infrastructure), .root (used for root servers), and .int (used for international treaty organizations).
These different types of domains serve various purposes and help categorize and identify websites and resources on the internet.