Update dns-traffic-log-how-to.md to reflect the current GA behavior

[RutujaJadhav1710]

Coming from AzNet support engineer [email protected].

Azure security policy provide CNAME blockpolicy.azuredns.invalid instead of RCODE Servfail when blocked domain is queried.
RCODE Servfail was public preview behavior which has changed to CNAME since GA in July.

[learn-build-service-prod]

Learn Build status updates of commit a29f317:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/dns/dns-traffic-log-how-to.md	✅Succeeded

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[ShannonLeavitt]

@RutujaJadhav1710 - Please take a moment to agree to the CLA so we can process this PR.

[RutujaJadhav1710]

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[Copilot]

Pull Request Overview

Updates DNS traffic logging documentation to reflect GA behavior changes for blocked domains. The Azure security policy now returns a CNAME response pointing to blockpolicy.azuredns.invalid instead of the previous RCODE SERVFAIL error that was used during public preview.

• Updated dig command output to show current GA behavior with CNAME blocking response
• Replaced SERVFAIL status with NOERROR status and CNAME record to blockpolicy.azuredns.invalid
• Added complete dig output including ANSWER, AUTHORITY, and OPT sections

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[Copilot]

The timestamp shows a future date (2025) which appears to be incorrect. This should reflect a realistic date when the example was captured.

Suggested change

	;; WHEN: Mon Sep 08 11:06:59 UTC 2025
	;; WHEN: Fri Sep 08 11:06:59 UTC 2023

[ttorble]

@asudbring

Can you review the proposed changes?

IMPORTANT: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
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