If you gave that response at an interview, you'd be praised for knowing what a URL shortener is, then asked to drill into more detail. For example, what data store would you use for your hash table? What technology do you use for your web tier? Are those physically on the same box? OK, that's fine. Twitter just bought you and you have 48 hours until you're receiving 100,000 requests per second. What needs to change about your architecture? OK, good answer, good answer. We recently discovered that people are abusing our infrastructure to cloak links to pages delivering malware. We need to be able to ban a domain and yank all their links retroactively. How can you accommodate that? etc, etc
How would you guys answer this one?
Start by saying that you're capable of approaching that problem at multiple different levels of the stack, from the browser chrome to the networking layer to HTTPS to HTTP to Google's (presumed) infrastructure to the browser again. Ask where they want you to drill down. Networking? OK. Evince some knowledge of what DNS is. Mention that Google controls the records for google.com on a nameserver somewhere. Maybe talk about bind a little bit. Mention in a wee bit of detail how the A record propagates out to the rest of the network, including to the user's DNS server. Observe that since it is google.com it is certainly cached there (and is probably already in the OS's DNS cache to boot, you might add). Ask if the interviewer would like to hear about TCP/IP or SSL handshakes or what have you next.
If you gave that response at an interview, you'd be praised for knowing what a URL shortener is, then asked to drill into more detail. For example, what data store would you use for your hash table? What technology do you use for your web tier? Are those physically on the same box? OK, that's fine. Twitter just bought you and you have 48 hours until you're receiving 100,000 requests per second. What needs to change about your architecture? OK, good answer, good answer. We recently discovered that people are abusing our infrastructure to cloak links to pages delivering malware. We need to be able to ban a domain and yank all their links retroactively. How can you accommodate that? etc, etc
How would you guys answer this one?
Start by saying that you're capable of approaching that problem at multiple different levels of the stack, from the browser chrome to the networking layer to HTTPS to HTTP to Google's (presumed) infrastructure to the browser again. Ask where they want you to drill down. Networking? OK. Evince some knowledge of what DNS is. Mention that Google controls the records for google.com on a nameserver somewhere. Maybe talk about bind a little bit. Mention in a wee bit of detail how the A record propagates out to the rest of the network, including to the user's DNS server. Observe that since it is google.com it is certainly cached there (and is probably already in the OS's DNS cache to boot, you might add). Ask if the interviewer would like to hear about TCP/IP or SSL handshakes or what have you next.