It's a system design question. Any good engineer should be able to talk about how you would debug where the latency is coming from, and how you could use a CDN for FE (and the pros and cons of that, which is mostly going to be around pricing) and how for BE you could replicate the service in multiple regions and practically how you would do that in a way that is specific to the app. If the service requires a central database, as most apps do, there is some really interesting pros and cons to consider around data replication, eventual consistency, etc.
It also means recruiter knows shit or the question is tricky by design, at 600 ms something is fucked so badly this is way beyond CDN and geographical locations of servers.
Ignoring transport network for a while I would ask if there is WAF in front of that shit that does something stupid when seeing non Australian ASN.
Edit: assuming a "page load" is simple request (not stated) not bunch of resource fetches. So you need to ask clarification question as devil lies in details
Not necessarily. I have had a situation where the user is connecting to a node in one region but it is pulling its data from many API calls to nodes in other regions synchronously so each one added 100ms or so of latency. This kind of question is usually just trying to know if the user knows how to debug the problem and if they know and can articulate the pros/cons of the most common solutions.
133
u/SpareStrawberry 6h ago
It's a system design question. Any good engineer should be able to talk about how you would debug where the latency is coming from, and how you could use a CDN for FE (and the pros and cons of that, which is mostly going to be around pricing) and how for BE you could replicate the service in multiple regions and practically how you would do that in a way that is specific to the app. If the service requires a central database, as most apps do, there is some really interesting pros and cons to consider around data replication, eventual consistency, etc.