Socket address is :

Question

Socket address is :

Accepted Answer

The correct option is (2):
A socket address is the fundamental identifier used by the Transport Layer protocols (like TCP and UDP) to uniquely define a specific process running on a specific host on a network. Since a host can run multiple applications simultaneously (e.g., a web server, an email client, and a game), merely having the IP address, which only identifies the *host* (computer), is insufficient to direct the data. The socket address is therefore a logical pair consisting of the **IP address** and the **port address**. The IP address ensures the data packet reaches the correct computer, while the port number specifies the exact application or service process on that computer that should receive the data, thus enabling end-to-end communication between two specific programs.

The incorrect option is (1):
This option, "IPv4 address translated to IPv6 address," describes a specific technical mechanism for network layer address transition, such as tunneling or dual-stack implementation, which is not the definition of a socket address. A socket address is a logical concept essential for inter-process communication, which exists irrespective of the specific version of the Internet Protocol (IP) being used. While an IP address is an essential *component* of the socket address, the translation process itself is a network engineering detail and does not define the compound socket structure (IP + Port).

The incorrect option is (3):
A socket address is a logical address structure that is meaningful from the Network and Transport layers upwards, consistently using the IP address and port number. The MAC address (Media Access Control), however, is a physical address used by the Data Link layer (Layer 2) to identify a network interface card within a local network segment. Furthermore, a domain address (like google.com) is a human-readable name that must first be resolved by the Domain Name System (DNS) to an IP address before a socket can be established. Therefore, combining the MAC and domain address incorrectly mixes physical addressing with a high-level naming scheme, confusing the layers of the TCP/IP model.

The incorrect option is (4):
While the ultimate destination of data is an application, the "Application layer address" is too abstract and general to serve as a socket address. The term application layer address could refer to a Uniform Resource Locator (URL) or an email address, which are conceptual addresses used by the application protocols themselves. The socket address (IP address + port address) is the concrete, lower-layer mechanism provided by the Transport Layer (Layer 4) to accurately demultiplex the incoming stream of network data to the exact application process that opened the socket, bridging the gap between the network and the specific program.