The documentation of the Domain Alias module mentions that the aliases should be visible in the Domain List:
3. Alias Management The Domain Alias module adds a new column to the Domain List table. If you go to the Domain List at Admin > Build > Domains > Domain List. You should now see an "Aliases" column in your domain list.
But this column is not there, I looked through the code and did not find any form_alter that could inject this column. Rather than fix the documentation, wouldn't it be nice to actually provide this column so the aliases can be seen at a glance? :)
Same goes for the shortcut to add an alias which should be present in this fabled column, it would be great to actually have this:
3.1 Creating Aliases To create a new alias, go to the Domain List at Admin > Build > Domains > Domain List. You should see an "Aliases" column in your domain list. Click on the 'add alias' link. You will be presented with a form divided into two parts. The top section, 'Registered aliases for *' will be empty initially.