So I needed to connect to a remote server to install some debian packages. I was trying to configure network settings to allow me access outside.

But my coworker said to just connect to his own laptop and I can access the packages that way.

So I setup in my /etc/hosts file, "132.21.23.45 packages.xyz.com"

My own IP is 10.x.x.x.

I tried to ping 132.21.23.45, but it didn't work.

Yet, sudo apt-get update worked and I was able to get some packages.

How does this work? Just by putting an IP address in /etc/hosts, I can't ping it, but I can connect and grab packages? So confused.

I can't say with any certainty what was going on in your situation, but there's no reason his system has to respond to a ping. Pings could be blocked on his machine, so you'd never get a response even though other services are working just fine.

Ping is a poor choice to use as a test anymore. It is blocked by default for many reasons.

To avoid DDOS attack ping is usually blocked. You may try traceroute instead. Or plain http download (if setup).

This article might tell you more: http://www.linuxhowtos.org/Security/disable_ping.htm

A search for "block ping" will turn up many more links. Some of them are useful.