1. Incident Definition

Incident Summary: Publisher ad server (GAM 360) logs indicate higher/lower billed impressions than the programmatic DSP buyer reporting.
Reported Variance: Discrepancy exceeds standard 5% SLA threshold (e.g. >15% billing discrepancy).
Severity Level: P1 Revenue Impact / Billing Reconciliation Hold.

2. Scope & Boundaries

• Inventory Slices Impacted: Specific Ad Unit (/12345/homepage_top), Device (Mobile Web iOS), Domain (example.com).
• Demand Partners Involved: Primary SSP exchange, downstream DSP buyer, and third-party measurement vendor (IAS / DoubleVerify / MOAT).
• Timeline Window: Last 7 days / specific campaign flight dates.

3. Data Sources & Log Assets Required

• Publisher Ad Server Raw Log Exports (GAM Data Transfer Files / Impression Events).
• SSP Exchange Auction Logs (Bid Requests, Bid Responses, Win Notices nurl, Billed Impressions).
• DSP Buyer Reporting (Billed Impressions, Cleared CPMs, Render Pings).
• Third-Party Verification Logs (Measured Impressions, Invalid Traffic IVT Flags).

4. Timestamp & Timezone Alignment

• Convert all disparate datasets to a unified timezone standard (UTC or EST).
• Slice data into identical 1-hour time buckets to observe divergence curves.
• Check for Daylight Saving Time (DST) offsets across multi-regional ad server nodes.

5. Request → Response Funnel Stage Inspection

1. Ad Opportunity (Slot Requested): 100,000
2. Bid Requests Dispatched to SSP: 98,500 (1.5% drop = network latency / prebid timeout)
3. Valid Bid Responses Received: 65,000 (34% no-bid rate = targeting / floor rejection)
4. Auction Won (Prebid / Dynamic Allocation): 12,000
5. Ad Markup Injected into Client DOM: 11,900
6. First Frame Rendered (<Impression> Beacon): 10,800 (9.2% drop = page navigation / render abort)
7. DSP nurl Win Notice Fired: 10,750
8. Third-Party Verification Measured: 9,200 (14.4% drop = IVT filter / viewability threshold)

6. Ad Server Configuration Comparison

• Confirm Line Item Type: Price Priority (P12) vs Ad Exchange vs Sponsorship (P4).
• Check Pacing & Impression Goal settings: Evenly vs Frontloaded vs As Fast As Possible.
• Verify Unified Pricing Rules (UPR): Confirm minimum floor rates did not reject bids during real-time auctions.

7. SSP / DSP Protocol Comparison

• Verify OpenRTB nurl vs burl execution: Did the DSP bill upon auction win notice (nurl) or billing notice (burl)?
• Check auction timeout ceiling (tmax): Ensure bids returned within configured threshold (e.g. 1000ms).
• Audit Currency Conversion: Confirm SSP and DSP operate in identical currencies without exchange rate mismatch.

8. Measurement & Attribution Logic Check

• Publisher Bills On: Ad Call Response / Header Injection vs Rendered First Frame.
• Buyer Bills On: VAST <Impression> Fired vs OMID Verified In-View (50% for 1 sec).
• Audit IVT (Invalid Traffic) Deductions: Check General Invalid Traffic (GIVT) and Sophisticated Invalid Traffic (SIVT) filter drops.

9. Privacy & Regulatory Consent Check

• Validate regs.ext.gdpr = 1 compliance: Confirm user.ext.consent exists and Purpose 1 (Device Storage) is granted.
• Check US Privacy Strings: Confirm regs.gpp / us_privacy signals do not restrict personalization.
• Verify CMP Execution Timing: Confirm CMP initialized before GPT and Prebid script execution.

10. Root Cause Classification

Primary Failure Mechanism: Metric Definition Mismatch: Publisher billing on Ad Server Delivery while DSP bills strictly upon OMID-verified <Impression> execution on slow-loading mobile connections.

11. Remediation Plan

1. Update contract billing SLA to align on Rendered Impressions (<Impression> beacon).
2. Lazy-load ad slots below the fold using IntersectionObserver with 200px viewport prefetch margin to eliminate render abort drop-offs.
3. Optimize creative asset payloads to reduce TTFB latency from 1800ms to <400ms.

12. Verification & Monitoring

• Deploy fix to 10% canary traffic slice.
• Monitor hourly discrepancy index: Confirm variance drops from 18.5% to <3.2%.
• Review 72-hour sustained reporting parity across GAM, SSP, and DSP log exports.

13. Incident Closure

Incident Status: RESOLVED.
SOP Documentation Updated: YES.
Executive Sign-off: Completed.