Hey just a quick note before doing the next few lectures. A recent June 2017 change in the official nginx image https://hub.docker.com/_/nginx (nginx  or nginx:latest ) removes ping, but I use it in the next few videos to test connectivity, so you might get an error about "ping not found". I'm working on updates to those videos but until I can get them processed and uploaded, just do this:

Anywhere I do a docker container run <stuff> nginx , where nginx  is the image you should use, replace that with nginx:alpine , which still has ping command in it.

There are other ways to solve this, including adding the ping util with apt-get, making your own image, etc. More info in this Q&A answer.