Free DNS Management System For Any Number Of Domains – EntryDNS
If we purchase a domain from a company who doesn’t offer free DNS management and want to customize its DNS records (like pointing MX records to Gmail), that’s when a solid DNS service is needed.
EntryDNS is a completely free DNS management service which allows any number of domains and records being created.
It has support for providing free DNS addresses for dynamic IPs as well (with the domain emtrydns.org).
And, there is a REST API for modifying DNS records which is useful for integrations with 3rd party apps.