DNS on AWS / GCP

I have a zone that's hosted by AWS route53 called sysdeseng.com. My goal was to create a few machines on GCP and have them resolve to a delegated subdomain.  For example:

test.scollier-gcp.sysdeseng.com

These are the steps required to do this:

1. Create the zone on "GCPs Network Services", "Cloud DNS"

• Give it a Zone name
• Give it a DNS name: scollier-gcp.sysdeseng.com
• Provide a description
• Click Create
• Note the name records, for example:
• ns-cloud-a1.googledomains.com.
• ns-cloud-a2.googledomains.com.
• ns-cloud-a3.googledomains.com.
• ns-cloud-a4.googledomains.com. 

2. Go to AWS route53 and create a NS record for this zone under the sysdeseng.com domain.

• Click on the sysdeseng.com zone in route53
• Create a record set
• On the right hand side, provide the name: scollier-gcp
• Change the type to NS
• Copy the nameservers from GCP and paste into the NS record.
• Click Create

3. Create the A record on GCP

• Return to GCP
• Go to "VPC Network", then "External IP Addresses"
• Create an external IP address, note it
• Go back to "GCPs Network Services", "Cloud DNS" and click the zone
• Add a record set
• Give it a DNS Name
• Provide the external IP address 
• Click Create

4. Test that it works

• Go to Linux terminal

$ dig +short testing.scollier-gcp.sysdeseng.com.

   34.67.155.244

$ dig +short SOA scollier-gcp.sysdeseng.com

ns-cloud-a1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300

$ dig +short SOA sysdeseng.com

ns-679.awsdns-20.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400