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312-50V9 · Question #491

While checking the settings on the internet browser, a technician finds that the proxy server settings have been checked and a computer is trying to use itself as a proxy server. What specific octet…

The correct answer is B. 127.0.0.1. The IPv4 loopback address 127.0.0.1 causes a computer to route traffic back to itself, so a browser using it as a proxy is treating the local machine as the proxy server.

Scanning Networks

Question

While checking the settings on the internet browser, a technician finds that the proxy server settings have been checked and a computer is trying to use itself as a proxy server. What specific octet within the subnet does the technician see?

Options

  • A10.10.10.10
  • B127.0.0.1
  • C192.168.1.1
  • D192.168.168.168

How the community answered

(35 responses)
  • A
    3% (1)
  • B
    86% (30)
  • C
    3% (1)
  • D
    9% (3)

Why each option

The IPv4 loopback address 127.0.0.1 causes a computer to route traffic back to itself, so a browser using it as a proxy is treating the local machine as the proxy server.

A10.10.10.10

10.10.10.10 is a routable private IP address in the class A RFC 1918 range that identifies a specific remote host, not the local machine.

B127.0.0.1Correct

127.0.0.1 is the IETF-reserved IPv4 loopback address defined in RFC 5735, which always resolves to the local host regardless of network configuration. When a browser proxy setting points to 127.0.0.1, all HTTP traffic is forwarded to a listener on the same machine, meaning the computer is functioning as its own proxy. This configuration is commonly used by local interception tools such as Burp Suite and Fiddler.

C192.168.1.1

192.168.1.1 is a private IP address typically assigned to a default gateway or home router and does not refer to the local host.

D192.168.168.168

192.168.168.168 is an arbitrary private IP address that could belong to any device on the local network and has no special loopback meaning.

Concept tested: IPv4 loopback address identifying local host as proxy

Source: https://www.rfc-editor.org/rfc/rfc5735

Topics

#loopback address#127.0.0.1#proxy server#network addressing

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