Computer Networks

DNS stands for Domain Name System, which translates domain names (like google.com) into IP addresses that computers use. 'Naming' (B) and 'Native' (C) are incorrect terms. 'Stack' (D) refers to TCP/IP stack, not DNS.

WAP (Wireless Application Protocol) is a technical standard for accessing information over mobile wireless networks like 2G/3G cellular networks. It enabled mobile phones to access simplified web content and services before modern smartphones, though it was limited by slow speeds and basic displays. WAP created a foundation for mobile internet access, leading to today's sophisticated mobile web browsing capabilities.

RARP stands for Reverse Address Resolution Protocol. It is used by a diskless machine to obtain its IP address from its server.

This software in computer system usually runs on a proxy server of an organization and controls the flow of incoming and outgoing messages.

Hyper Text Transfer Protocol

ARP (Address Resolution Protocol) dynamically maps IP addresses to physical MAC addresses. When a device needs to communicate with another IP address on the same local network, it broadcasts an ARP request to discover the corresponding hardware address.

ARP (Address Resolution Protocol) requests are broadcast messages sent to all hosts on a local network to discover the MAC address associated with a known IP address. Broadcast ensures all devices receive the request, but only the target IP responds.

The IP header has a minimum size of 20 bytes (when no options are present) and can extend up to 60 bytes (when options are included). The IHL (Internet Header Length) field specifies the header length in 32-bit words.

 An ARP reply is unicast response to a broadcast request.

BGP (Border Gateway Protocol) is a path vector routing protocol that exchanges reachability information between autonomous systems. It carries the full path of AS numbers to prevent routing loops and apply policy-based routing.

POST is the HTTP method used to send data to the server in the request body. Unlike GET (which retrieves data), POST is designed for submitting information to be processed by the server.

A DNS resolver is the client-side component that initiates DNS queries on behalf of applications. It sends queries to DNS servers and caches responses for future use, acting as the client in the DNS system.

A secondary DNS server obtains its zone data by transferring it from a primary DNS server through zone transfer (AXFR/IXFR). This provides redundancy and load distribution for DNS services.

LCP (Link Control Protocol) packets in PPP serve three key purposes: configuration (establishing connection parameters), termination (closing connections), and option negotiation (agreeing on protocol parameters like authentication methods). Option D covers all these functions.