In the next assignment, you'll be using the tool nslookup inside the alpine:latest image, but in early 2020 there was a bug introduced to the latest Alpine image 3.11.3 that affects how nslookup works on hostnames, so for the next Assignment on DNS Round Robin, either change your command to work around it with nslookup search. (with a dot added) or use an older Alpine image like alpine:3.10. 

Hopefully, they'll fix it soon. I'm tracking this bug: https://github.com/gliderlabs/docker-alpine/issues/539