This synthetic record: Once you set up the Dynamic DNS synthetic record, you must set up a client program on your host or server (the resource behind the gateway) or on the gateway itself that detects IP address changes and uses the generated username and password and communicate the new address to the Google name servers. IPv6 addresses are typically not dynamically assigned.
Tip: Directing a wild card (*) to a dynamic resource: While you cannot use a wildcard in a Dynamic DNS record, you can direct a wildcard to your naked domain or a particular subdomain with a CNAME record.
The period of validity may vary from just seconds to days or even weeks.
For example, the TTL on Dream Host’s server is set to 4 hours by default.
To this end, the DNS resolution process allows for (i.e., the local recording and subsequent consultation of the results of a DNS query) for a given period of time after a successful answer.
As you can see, all the script needs is a CSV file with 2 columns called “hostname” and IP, containing the FQDN, and the DNS server you want to connect and make the changes.The word "propagation" implies that DNS changes spread from DNS server to DNS server, and that you have no control over how quickly it happens.In fact, DNS servers check in with your local DNS server as needed, and the administrator of your local DNS server controls the 'time to live' (TTL) values for all DNS records in your domain.It’s important to note that since it can take several hours for DNS records to resolve in all locations, different computers in different locations see the update at different times.Many people incorrectly refer to a mysterious 48 hour or 72 hour propagation time when you make a DNS change.