When you're launching your deployment, the system requires an AD DNS Name. This field adds your preferred name to the local AD domain which is created for each deployment. Just like each deployment is created with it's own GCP Project, each deployment requires a separate local AD DNS.
AD DNS Name field requirements:
Name example: dnsname.local
Maximum number of characters:
with 1 dot (name1.end1): from 1 to 14 letters or numbers in front and 1 to 14 letter or numbers after the dot
with 2 dots (name1.name2.end1): from 1 to 14 letters or numbers before the first dot, from 1 to 14 letters or numbers after the first dot and from 1 to 5 letters or numbers after the second dot
with 3 dots (name1.name2.name3.end1): from 1 to 14 letters or numbers before the first dot, from 1 to 14 letters or numbers after the first dot and from 1 to 5 letters or numbers after the second dot