LinkedIn Senior Software Engineer Interview Experience — Five Rounds, Failed AI Coding and System Design

LinkedIn Senior Infra, five rounds. I failed AI Coding and System Design, so here are some lessons learned (I had AI polish this a bit).

I recently finished the interview loop for a LinkedIn Senior Infra role and did not pass, mainly because of AI Coding and System Design. My memory is still fresh, so I'm sharing the questions and my own review, hoping it helps anyone preparing for Infra.

1. Phone screen

Two LeetCode problems:

LC 152

LC 53

It went fairly smoothly overall.

2. Virtual Onsite

BQ

Pretty standard behavioral questions, mostly about leadership, ownership, teamwork, and problem solving.

I'd suggest preparing your project stories ahead of time, especially ones that show your personal contribution, technical decisions, and impact.

LC Coding

The first problem was topological sort, with a follow-up of using DFS to find the distance between two nodes.

I did well in this round, and the earlier rounds had all gone pretty smoothly.

AI Coding (failed)

This was my first AI Coding interview, I was very uncomfortable with it, and it was the round where I stepped on the most landmines.

The problem came with a fairly long requirements description and a few code files, and I had to implement log processing on top of the existing code. It was roughly three parts:

Classify logs by priority, where the priorities have a clear order.

Write tests for the feature I implemented.

Given a specified time, return the logs in the corresponding time window.

The biggest lesson from this round: first understand the requirements, the existing code structure, and your implementation plan yourself, and only then ask the AI to help write code, instead of directly asking the AI how to implement it.

In the actual interview the requirements were long and the code was spread across several files. If you haven't built a clear plan in your head first, it's very easy to get led around by the AI, and in the end you can't control the code logic.

I think AI Coding doesn't only test whether you can use AI. It also tests basic code reading, breaking down requirements, awareness of testing, and whether you can verify that the AI-generated code is correct.

If you haven't done this kind of interview before, I'd suggest practicing in advance: understanding requirements in an existing codebase, modifying code, adding tests, and handling follow-ups.

System Design (failed)

The question was to design a distributed Key-Value Store, in a setting closer to internal use at a small company.

I had specifically practiced this question before and thought I was well prepared, but I still didn't meet the bar.

Looking back, there were mainly these problems.

First, I didn't compare solutions enough.

I immediately proposed a Coordinator + Consistent Hashing design without properly discussing other architecture options, for example:

Centralized: a Coordinator handles node management and request routing.

Decentralized: nodes shard and route among themselves through something like consistent hashing.

Hybrid: keep the data plane as decentralized as possible, with a separate Control Plane managing nodes and cluster metadata.

If you just present one design, it's easy to overlook its limitations. For example, a centralized Coordinator can become a bottleneck or a single point of failure on the request path, depending on whether it takes part in every request and whether it has redundancy.

I think the better approach is to proactively compare the pros and cons of the different options, then settle on a suitable design together with the interviewer based on the scale, latency requirements, consistency needs, and operational complexity in the problem, rather than throwing out one design and waiting for the interviewer's feedback.

Second, I didn't go deep enough on the key distributed systems problems.

Even a simple-looking KV Store has a lot worth digging into:

Hot Key: how do you handle hot data and traffic skew?

Scaling nodes in and out: when adding or removing nodes, how do you minimize data migration?

Node failure: how do you detect failures, reroute requests, and recover service?

Replication: how are replicas placed, and how do you recover from failures?

Consistency: how do you define read/write consistency, and how do you handle concurrent writes?

Data Migration: how do you handle reads and writes that keep arriving during scaling or migration?

Availability: how do you avoid single points of failure and keep serving when some nodes are unavailable?

You don't have to expand all of these in detail at the start, but you need to identify them proactively and go deeper step by step based on what the interviewer cares about.

Third, you need both technical depth and breadth.

My feeling is that a Senior Infra system design isn't just getting an architecture drawn. You also have to explain why you chose it, what the alternatives are, what the trade-offs of each are, and what goes wrong when there are failures or the system grows.

The lesson this time: you can't assume that because you've practiced a classic problem you will definitely pass. What you really need to master are the design principles behind it, and the ability to make sound technical decisions under different constraints.

Personally I think system design needs to reach the level where you can analyze a problem independently and systematically, and proactively push the discussion deeper. For regular prep you can use Hello Interview's explanations as a reference, but it matters more to do full, timed practice yourself rather than only reading answers.

3. Overall thoughts and summary

This interview made me feel that Senior Infra interviews really do cover a lot of ground. Besides the traditional algorithms and system design, you may now also get AI Coding, plus low-level programming like multithreading, locks, and concurrency control.

For Infra in particular, you can't prepare only LeetCode and System Design. You also need to be comfortable developing in a real codebase and with correctness problems in multithreaded scenarios.

So far I've boiled it down to five prep areas:

LeetCode algorithms: the basics still matter. You need coding speed, correctness, and the ability to handle follow-ups.

BQ: prepare project stories with technical depth and real impact.

Multithreading / Concurrency: understand locks, thread safety, synchronization primitives, producer-consumer and other common problems, and practice actually coding them.

System Design: don't just draw the architecture. Compare options, analyze trade-offs, and proactively go deep on the key distributed systems problems.

AI Coding: get used to reading code in an existing codebase, breaking down requirements, using AI to help implement, writing tests, and verifying the result.

My personal feeling is that System Design is especially important for Senior Infra, but no other round can have an obvious weak spot either. Even with good overall experience and project background, if one round clearly falls short of the bar, it can directly affect the final result.

The biggest takeaway this time: preparing for interviews can't just be about having "done this problem before". You have to make sure you can do it independently, explain the design trade-offs, and keep going deeper through follow-ups.

All of the above is my personal experience and review, and it may not apply to every LinkedIn team. Hope it helps, and I'd welcome discussion from anyone with experience on how to prepare for Senior Infra AI Coding and System Design. Thanks everyone!