Typically the designate client talks to Keystone (or a Keystone like service) via the OS_AUTH_URL setting & retrives the designate endpoint from the returned service catalog. Using --os-endpoint or OS_ENDPOINT you can specify the end point directly, this is useful if you want to point the client at a test environment that’s running without a full Keystone service.
$ designate --os-endpoint http://127.0.0.1:9001/v1 server-create --name ns.foo.com.
+------------+--------------------------------------+
| Field | Value |
+------------+--------------------------------------+
| created_at | 2013-07-09T13:20:23.664811 |
| id | 1af2d561-b802-44d7-8208-46475dcd45f9 |
| name | ns.foo.com. |
| updated_at | None |
+------------+--------------------------------------+
$ designate --os-endpoint http://127.0.0.1:9001/v1 domain-create --name testing123.net. --email simon@mccartney.ie
+------------+--------------------------------------+
| Field | Value |
+------------+--------------------------------------+
| name | testing123.net. |
| created_at | 2013-07-09T13:20:30.826155 |
| updated_at | None |
| id | 5c02c519-4928-4a38-bd10-c748c200912f |
| ttl | 3600 |
| serial | 1373376030 |
| email | simon@mccartney.ie |
+------------+--------------------------------------+
$ designate --os-endpoint http://127.0.0.1:9001/v1 record-create --name myhost.testing123.net. --type A --data 1.2.3.4 5c02c519-4928-4a38-bd10-c748c200912f