Computer Networks

Answer

(i) with external access

Explanation

A proxy server acts as an intermediary between a client and another server, commonly on an external network such as the Internet. Instead of directly contacting the destination server, the client sends its request to the proxy, and the proxy forwards the request and returns the response.

A proxy can provide functions such as:

• Controlled external access to Internet resources.
• Caching frequently requested content.
• Filtering and access control according to organizational policies.
• Privacy/security by hiding internal client details from external servers in some configurations.

Option analysis

• (i) with external access: Correct in the context of this MCQ. A proxy mediates access between an internal client and external resources.
• (ii) acting as a backup: Backup servers are used for redundancy/data recovery, not as the primary definition of a proxy.
• (iii) performing file handling: File handling is not the defining purpose of a proxy server.
• (iv) accessing user permissions: A proxy may enforce access policies, but user-permission management is not its fundamental role.

Final answer: (i) with external access.

Answer

(i) End systems

Explanation

The Application layer contains protocols and services used directly by network applications such as HTTP, SMTP, DNS, and FTP. These application processes run on end systems (hosts) rather than on intermediate forwarding devices such as routers or switches.

Final answer: (i) end systems.

Answer

(i) End systems

Explanation

The Application layer contains protocols and services used directly by network applications, such as HTTP, DNS, SMTP, and FTP. These applications run on end systems (hosts).

NICs and Ethernet are associated with lower networking layers, while routers are intermediate forwarding devices.

Final answer: (i) End systems.

Answer

(iii) HTTP allows information to be stored in a URL is the FALSE statement.

Explanation

• (i) HTTP runs over TCP: True in the traditional HTTP/1.0, HTTP/1.1 and HTTP/2 model. (HTTP/3 uses QUIC over UDP, but that is outside the traditional framing of this PYQ.)
• (ii) HTTP describes the structure of web pages: In exam terminology, HTTP is the Web's application protocol for requesting and transferring resources; HTML actually describes the structure of web pages. Thus this wording is imprecise, but it is not the intended false option in the question.
• (iii) HTTP allows information to be stored in a URL: False. A URL identifies/locates a resource; HTTP is the protocol used to request and transfer that resource. Information such as query parameters can be encoded in a URL, but HTTP itself does not 'store' information in the URL.
• (iv) HTTP can be used to test the validity of a hypertext link: True in the traditional HTTP model; methods such as HEAD can be used to check resource availability without retrieving the full representation.

Final answer: (iii).

Answer

(i) Video conferencing

Explanation

UDP is connectionless and does not provide TCP-style reliable, ordered delivery. This makes it useful for real-time applications where low delay is more important than retransmitting every lost packet.

In video conferencing, a small amount of packet loss may be preferable to the delay caused by retransmission. Real-time media applications can also use application-level mechanisms to handle loss.

• WWW: Traditionally uses TCP (modern HTTP/3 uses QUIC over UDP, but this question follows the traditional model).
• Email: Uses TCP-based protocols such as SMTP.
• Online chess: Usually prioritizes reliable delivery of moves and can use TCP.

Final answer: (i) Video conferencing.