UGC NET Questions (Paper – 1)

A firewall acts as a barrier between a trusted internal network and untrusted external networks such as the internet. It inspects traffic according to predefined rules and decides whether to allow or block specific packets. This helps prevent unauthorised access and reduces the exposure of internal systems to external threats. Therefore, the mechanism described is a firewall.

Option A:
Option A is correct because firewalls are explicitly defined as security systems that enforce an access control policy between networks, matching the role outlined in the stem. They can be implemented in hardware, software or a combination of both.

Option B:
Option B, gateway, is a broader term for a device or software that connects networks using different protocols and may not necessarily enforce detailed security rules.

Option C:
Option C, bridge, connects network segments at the data link layer and forwards frames based on physical addresses, without usually providing extensive security filtering.

Option D:
Option D, proxy server, can add some security by mediating requests but is primarily designed for caching and content control rather than acting as the main perimeter filter.