Yelp Software Engineer - Intern interview questions

I was emailed to set up a phone interview within two weeks of submitting my application online. After sending them my availability, the interviewer responded a few minutes later saying he was going out of town the next day and asked if I could interview within the hour. Expecting a nontechnical interview, I said yes, and was bombarded by very technical questions, most of which I was completely unprepared for.

The first interview was through phone and consisted of technical questions and some interpersonal ones. He asked me questions like: why Yelp? grep questions? how many bytes are in an integer? what's the max number that can be represented using unsigned integers? explain with the most detail what happens in the background after a URL is put in the browser and pressed enter. some linux commands: pid. What's the protocol used in HTTP? What's SSL? The second interview is throuh Skype. What's the most challenging thing you've done? What's the difference between a process and a thread? It's where memory and state is not shared and the other one is. Then through screenshare, he gave me this problem to code: We have a fairly large log file, about 5GB. Each line of the log file contains an url which a user has visited on our site. We want to figure out what's the most popular 100 urls visited by our users.