L5 Software Engineer, Ads Interview Experience

I talked through my ads background, especially my multiformat ads experience and the fact that I know the publisher side well. I got the sense that was exactly why they reached out in the first place. The whole thing felt less like a deep sell and more like them checking whether my background matched what the ads org is staffing for.

What compensation are you expecting for this role?

I gave a number based on Levels and said I was seeing around 500 for this role. The recruiter was fine with it and didn't push back. In hindsight I probably should not have anchored that early, but that is how the conversation went.

I wrote a straightforward TTL cache in JavaScript, then we talked through the gotchas. I said if I keep everything in memory and never really evict, the cache just keeps growing. For lazy eviction, the same issue shows up if expired entries are never cleaned up. I suggested regular compaction or cleanup on a cadence. The vibe was less, can you grind code, and more, do you understand the failure modes of something you'd actually build.

The org chart was a tree of employees and direct reports. One part was computing each person's level, another was deciding whether someone was balanced by comparing how many people were above them versus below them, and the last was building a histogram by level. I initially thought about solving each part separately, but the interviewer nudged me toward doing it in one loop. I was shaky here, and he basically steered me to the final shape of the solution.

This was the one I really screwed up. I reached for a failed project from my resume, but I had forgotten a bunch of the details, so I kind of mumbled my way through it and never really landed the story. It was supposed to be about how I helped shape a product decision with PM, but I felt totally unprepared and honestly felt like I was about to have a heart attack while answering.

I gave my usual why Netflix spiel, and they pretty much just moved on. It felt like a checkbox, not a deep motivation conversation.

I framed it around the core business objects you need to run ads: advertiser setup, campaigns, the ad or line item itself, targeting data, frequency cap settings, and revenue or event records. I had prepped this really hard off the job req, so I could talk through the entities coherently instead of hand-waving. This round felt like pure domain fluency.

I treated it a lot like a rate limiter plus ad event ingestion. I talked through enforcing caps like five times a day or ten times in two weeks, and I leaned on click or impression tracking patterns for the event side. The big nuance I called out was granularity: you can cap at the line item, campaign, or category level. Google Ad Manager docs were actually really useful for those specifics.