In the networking lecture, it is said that a container can reference another container by using it’s name, which is possible due to Embedded DNS.
If this is true, why should we use --link flag in Example Voting Application containers?
As you say Docker’s embedded DNS allows containers to communicate by name within user-defined networks. The --link flag is unnecessary for most use cases and is now deprecated. If you give a link to the slide we can look at getting it updated.