How to use this page

This guide is designed to help you answer quickly and clearly in interviews. Keep your explanations short, operational, and easy to understand. If an interviewer asks a deeper question, then expand into delivery logic, targeting, auction mechanics, troubleshooting steps, and tradeoffs.

Interview strategy:

Start simple, then go one level deeper. A strong Solution Engineer answer usually explains what something is, why it matters, and where you would check it in a real setup.

What we will cover

100 interview questions with short answers 10 troubleshooting scenarios based on real delivery issues 5 practical tasks for your GAM mock project
Part 1100 interview questions and short answers Part 2Real-world troubleshooting scenarios Part 3Practical GAM mock-project tasks Prep planA simple way to revise before interviews

Part 1: Ad Serving + GAM interview questions with answers

Basic Ad Serving (Q1-Q20)

# Question Short answer
Q1What is an Ad Server?An ad server is a system that stores ads and delivers them when a page, app, or CTV stream loads.
Q2What is an Ad Request?It is the request sent when a webpage or app loads and asks the ad server for an ad.
Q3What is an Ad Impression?An impression is counted when an ad is successfully displayed.
Q4What is a Click?A click happens when a user clicks on an ad.
Q5What is CTR?CTR = Clicks / Impressions.
Q6What is Fill Rate?Fill Rate = Impressions / Ad Requests.
Q7What is eCPM?eCPM = Revenue / Impressions x 1000.
Q8What is Frequency Capping?It limits how many times the same user sees an ad.
Q9What is Targeting?It means showing ads based on rules such as location, device, audience, or content.
Q10What is Creative?The creative is the actual ad file, such as an image, video, HTML tag, or VAST asset.
Q11What is a Line Item?A line item is the campaign setup inside GAM that controls delivery rules.
Q12What is an Order?An order is the advertiser campaign container that holds one or more line items.
Q13What is Inventory?Inventory means the ad spaces available on a website, app, or CTV environment.
Q14What is an Ad Unit?An ad unit is a specific placement such as homepage_top_banner.
Q15What is a Passback Tag?If GAM cannot fill the slot, a passback tag sends the request to another network.
Q16What is a House Line Item?It is used for internal ads such as self-promotion or unsold inventory fill.
Q17What is a Sponsorship Line Item?It is a high-priority reserved line item used to secure inventory for one advertiser.
Q18What is a Standard Line Item?It is a guaranteed line item that delivers with pacing across the campaign window.
Q19What is Price Priority?It is a non-guaranteed line item type where higher CPM gets higher priority.
Q20What is Remnant Inventory?Remnant inventory is leftover inventory often sold through Ad Exchange or other demand.

GAM Setup (Q21-Q40)

# Question Short answer
Q21What is Key-Value Targeting?Custom targeting using parameters such as age=25 or interest=sports.
Q22What is Creative Size?The ad dimensions, such as 300x250 or 728x90.
Q23What is Roadblocking?Showing multiple ads from the same advertiser together on one page.
Q24What is Competitive Exclusion?It prevents competitor ads from appearing together.
Q25What is Day Parting?Running ads only during selected times of day.
Q26What is Geo Targeting?Targeting users by country, region, or city.
Q27What is Device Targeting?Targeting specific device groups such as mobile, desktop, or CTV.
Q28What is Delivery Rate?The speed at which a campaign is serving impressions.
Q29What is Pacing?Pacing spreads delivery across time so the campaign lasts until the end date.
Q30What is Overdelivery?Serving more impressions than were booked.
Q31What is Underdelivery?Serving fewer impressions than were booked.
Q32What is Forecasting in GAM?Forecasting predicts whether a campaign is likely to deliver based on eligible inventory.
Q33What is Creative Rotation?Rotating multiple creatives inside the same campaign.
Q34What is Ad Exchange (AdX)?Google Ad Exchange is Google's marketplace for real-time bidding.
Q35What is Dynamic Allocation?It lets AdX compete against direct campaigns for impressions.
Q36What is Unified Pricing Rule?A rule that sets floor prices across eligible demand sources.
Q37What is First Look?It gives preferred buyers priority access before open competition.
Q38What is Private Marketplace (PMP)?A PMP is an invite-only auction for selected buyers.
Q39What is Programmatic Guaranteed (PG)?A programmatic deal type with guaranteed impressions.
Q40What is Deal ID?A unique ID used to match PMP or PG deals between buyer and seller systems.

Waterfall vs Unified Auction (Q41-Q55)

# Question Short answer
Q41What is Waterfall?Waterfall calls demand partners one by one based on priority order.
Q42What is Unified Auction?Unified auction allows all demand to compete at the same time.
Q43Which usually gives higher revenue?Unified auction usually improves revenue because more demand competes fairly.
Q44Why did Waterfall exist?It existed because older ad tech stacks could not run parallel auctions well.
Q45What is the problem with Waterfall?A better bidder later in the stack may never get a chance to bid.
Q46What is Header Bidding?Header bidding runs an auction before the GAM ad server decision.
Q47What is Prebid.js?Prebid.js is a header bidding wrapper used to connect multiple bidders.
Q48What is a Timeout in Header Bidding?It is the maximum amount of time bidders get to return a bid.
Q49What happens if a bidder times out?Its bid is ignored for that auction.
Q50What is a Bid Response?The DSP response containing bid price, creative, and metadata.
Q51What is Win Price?The final price paid by the winning bidder.
Q52What is First Price vs Second Price Auction?In first price you pay your own bid. In second price you pay roughly the second highest bid plus a small increment.
Q53What is Bid Shading?Bid shading is when a DSP lowers its bid strategically in a first-price auction.
Q54What is Floor Price?The minimum price accepted to sell inventory.
Q55What is Hard Floor vs Soft Floor?A hard floor rejects bids below the threshold, while a soft floor allows auction logic to continue.

Troubleshooting (Q56-Q75)

# Question Short answer
Q56Why is a campaign not delivering?The most common reason is targeting that is too narrow.
Q57Why are impressions low?Usually low traffic, strong competition, or poor eligibility.
Q58Why are ad requests high but impressions low?That usually means a low fill rate.
Q59Why is the creative not showing?A common reason is creative size mismatch with the ad unit.
Q60Why are there clicks but no conversions?This often points to a tracking or attribution problem.
Q61Why is there a discrepancy between GAM and a DSP?Different systems count events differently and at different stages.
Q62Why do you see a VAST error?Common causes are timeout, invalid XML, or unsupported media response.
Q63Why is a blank ad showing?The creative may be blocked, broken, or loading over the wrong protocol.
Q64Why is AdX not competing?The floor price may be too high for current market demand.
Q65Why is Programmatic Guaranteed not delivering?The deal may not have enough matching inventory available.
Q66Why is PMP delivery low?The deal targeting may not match actual available traffic.
Q67Why did revenue drop?Usually fill rate dropped, CPMs dropped, or both happened together.
Q68Why is latency high?Too many bidders or slow responses can increase load time.
Q69Why is a CTV ad buffering?A slow VAST response or slow video asset can cause buffering.
Q70Why is there an SSAI issue?Ad stitching delays or server-side integration problems are common causes.
Q71Why is frequency capping not working?The platform may not recognize the user identity consistently.
Q72Why is geo targeting not working?IP detection can be inaccurate or mapped differently by vendors.
Q73Why was a creative rejected?Most often because of policy, quality, or security violations.
Q74Why is pacing uneven?Traffic distribution may be uneven throughout the campaign period.
Q75Why is a line item stuck in ready?The creative is often missing, inactive, or not yet approved.

Advanced (Q76-Q100)

# Question Short answer
Q76What is OpenRTB?OpenRTB is the standard protocol used for programmatic bidding.
Q77What is a Bid Request?The SSP sends a bid request to DSPs asking them to bid on an impression.
Q78What is a Bid Response?The DSP replies with its bid, creative, and related metadata.
Q79What is a Win Notice?A message telling the DSP that it won the auction.
Q80What is a Loss Notice?A message telling the DSP that it did not win the auction.
Q81What is IFA?IFA is a device advertising ID used in mobile and CTV environments.
Q82What is COPPA?COPPA is a US privacy law for protecting children online.
Q83What is GDPR?GDPR is the privacy regulation used across the European Union.
Q84What is schain?It is supply chain information that improves transparency in programmatic transactions.
Q85What is ads.txt?A publisher file listing authorized sellers of web inventory.
Q86What is app-ads.txt?The app equivalent of ads.txt for mobile inventory.
Q87What is VAST?VAST is the XML standard used to define video ad responses.
Q88What is VMAP?VMAP defines where ad breaks should occur in video content.
Q89What is an Ad Pod?An ad pod is a group of ads served in one video break.
Q90What is SSAI?Server-side ad insertion stitches ads into content on the server side.
Q91What is CSAI?Client-side ad insertion renders ads in the player on the device side.
Q92What is Quartile Tracking?Tracking video milestones at 25%, 50%, 75%, and 100% completion.
Q93What is Viewability?It measures whether an ad had a meaningful chance to be seen by a user.
Q94What is the MRC standard?It is the industry standard used to define measurable ad viewability.
Q95What is Brand Safety?Brand safety means avoiding unsafe or harmful content environments.
Q96What is Contextual Targeting?It targets based on the content of the page or stream rather than user history.
Q97What is Audience Targeting?It targets users based on behavior, intent, or profile data.
Q98What is a Lookalike Audience?A modeled audience similar to a known high-value audience segment.
Q99What is Attribution?Attribution identifies which touchpoint influenced the conversion.
Q100What is Postback?Postback is server-to-server conversion tracking between platforms.

Part 2: Troubleshooting scenarios (real-world)

Interviewers often move from definitions into scenarios. Use the pattern below: describe the symptom, explain the first place you would check, then propose a practical fix.

Problem Likely reason Where to check Practical fix
Line item not deliveringTargeting is too narrow or inventory is too limited.Line item targeting, forecast, matched ad units, creative status.Expand targeting, add inventory, or reduce restrictions.
Low impressionsLow traffic or stronger competing line items.Ad unit traffic, priority stack, delivery diagnostics.Increase eligible traffic or adjust line item priority and targeting.
High ad requests but low impressionsLow fill rate across direct and programmatic demand.Match rate, fill reports, no-fill logs, demand partner response.Improve demand coverage and review floors or targeting setup.
Creative not showingSize mismatch or unapproved creative.Creative association, ad unit sizes, policy and approval status.Attach the correct size creative and ensure approval is complete.
Clicks but no conversionsTracking tags, landing page, or attribution setup is broken.Click tracker, pixel firing, analytics events, conversion setup.Validate the full click-to-conversion path and fix tracking.
AdX not competingFloor price is too high or the inventory is not attractive enough.Unified pricing rules, bid response rates, historical CPM trends.Lower the floor or optimize inventory quality and viewability.
PMP underdeliveryDeal targeting does not match the actual traffic profile.Deal ID mapping, device or geo targeting, audience availability.Relax targeting or align the deal with available inventory.
Blank ad responseCreative loading issue, blocked assets, or HTTP/HTTPS mismatch.Browser console, creative markup, CDN and asset URLs.Use secure creative assets and fix broken resource calls.
High latencyToo many bidders or slow response times in the auction chain.Header bidding timeout, bidder logs, waterfall steps, network timing.Reduce bidder count, adjust timeout, and remove slow partners.
CTV or SSAI bufferingSlow VAST response, heavy media file, or stitching delay.VAST wrapper depth, video asset load time, SSAI server logs.Shorten wrapper chains, optimize media, and improve stitching latency.
Good interview phrasing:

"First I would check eligibility, then delivery constraints, then creative readiness, and finally auction competition." That structure sounds practical and shows you know how operators debug real issues.

Part 3: Your next practical tasks

The best way to convert interview theory into confidence is to build a small mock network and document what you learn. Use these tasks in your GAM mock project.

Task 1: Create a full GAM setup

  • Create 5 advertisers.
  • Create 10 orders.
  • Create 30 line items across Sponsorship, Standard, Price Priority, House, and AdX.

Task 2: Create inventory

  • homepage_top_728x90
  • homepage_sidebar_300x250
  • article_mid_300x250
  • video_preroll
  • CTV_preroll

Task 3: Create key-values

  • age = 20, 30, 40
  • device = mobile, desktop, ctv
  • geo = india, us, uk
  • content = sports, news, movie

Task 4: Create 10 problems and solve them

  • Line item not delivering -> narrow targeting -> expand targeting.
  • Low AdX revenue -> floor price too high -> reduce floor.
  • Creative not showing -> size mismatch -> fix creative size.
  • PG underdelivery -> low inventory -> increase inventory.
  • Blank ad -> SSL issue -> use HTTPS creative.

Task 5: Build a troubleshooting sheet

  • Problem
  • Possible Reason
  • Where to Check in GAM
  • Fix
  • Screenshot
  • Learning

Simple prep plan before the interview

  1. Revise the 100 questions until you can answer each one in one or two sentences.
  2. Practice explaining 5 to 10 troubleshooting scenarios out loud.
  3. Build the GAM mock project and keep screenshots of your setup.
  4. Prepare one short story about a delivery issue, what you checked, and how you fixed it.
Final takeaway:

For Ad Serving, GAM, and Solution Engineer interviews, strong candidates are not the ones who memorize the most terms. They are the ones who can explain platform logic simply, troubleshoot systematically, and show practical operator thinking.