NSE4 · Question #556
Which of the following statements are true when using Web Proxy Auto-discovery Protocol (WPAD) with the DHCP discovery method? (Choose two.)
The correct answer is C. The DHCP server provides the PAC file for download. D. If the DHCP method fails, browsers will try the DNS method.. When using WPAD with DHCP, the DHCP server provides the PAC file URL, and browsers will attempt DNS discovery as a fallback if the DHCP method fails.
Question
Which of the following statements are true when using Web Proxy Auto-discovery Protocol (WPAD) with the DHCP discovery method? (Choose two.)
Options
- AThe browser sends a DHCPINFORM request to the DHCP server.
- BThe browser will need to be preconfigured with the DHCP server's IP address.
- CThe DHCP server provides the PAC file for download.
- DIf the DHCP method fails, browsers will try the DNS method.
How the community answered
(15 responses)- A7% (1)
- C93% (14)
Why each option
When using WPAD with DHCP, the DHCP server provides the PAC file URL, and browsers will attempt DNS discovery as a fallback if the DHCP method fails.
While DHCPINFORM is used for requesting configuration information, clients typically receive the PAC file URL via standard DHCP lease options during the initial lease request or a subsequent renewal, not a dedicated DHCPINFORM for WPAD discovery specifically.
The browser does not need to be preconfigured with the DHCP server's IP address; it discovers the DHCP server automatically as part of the normal IP address acquisition process or uses existing DHCP information already obtained.
In the DHCP discovery method for WPAD, the DHCP server is configured with a specific option (commonly option 252) to provide the URL of the proxy auto-configuration (PAC) file to the client. The client then downloads the PAC file from this provided URL.
Browsers typically implement WPAD with a robust fallback mechanism. If the DHCP discovery method (e.g., failing to receive option 252) does not yield a PAC file URL, the browser will then attempt to use the DNS discovery method (e.g., querying for 'wpad.domain.com') to locate the PAC file.
Concept tested: WPAD Discovery Methods (DHCP and DNS)
Source: https://docs.fortinet.com/document/fortigate/7.4.0/fortios-cookbook/241775/wpad-file
Topics
Community Discussion
No community discussion yet for this question.