Layer 3 · Go deeper · 7 min
Go deeper
Size it, build it, then make the calls an interviewer will push you on.
Back of the envelope
Size it up
Tap through each step of the arithmetic.
How long would 400 sign-ups take with a certificate each?
How long to onboard 10,000 custom domains?
Build-up · 6 steps
Follow one request to Acme’s shard
One browser request for acme.app.example, from DNS to the database. Each hop needs only part of the answer.
Step 1 of 6
DNS: one wildcard record
One record, *.app.example, sends every tenant name to your edge. DNS knows nothing about tenants, so signing up kirana.app.example is just a catalog row.
4 interview moments
You’re the candidate
The interviewer pushes on the hard parts. Pick an approach and see how it holds up.
Deep dive 1 of 4
Interviewer
“Your SaaS has 200,000 tenants, many API integrations, and moves tenants between stamps often. How do requests reach the right stamp?”
Your move. Pick an approach:
Deep dive 2 of 4
Interviewer
“Sale day: 80,000 requests a second across 200,000 tenants. How does each router find a tenant’s stamp?”
Your move. Pick an approach:
Deep dive 3 of 4
Interviewer
“A customer brings 10,000 storefront domains to point at your platform. How do you get each one a certificate?”
Your move. Pick an approach:
Deep dive 4 of 4
Interviewer
“Tenants get subdomains like acme.app.example, and some publish custom themes with their own script. How do you scope the session cookie?”
Your move. Pick an approach: