End User                  dCDN                   uCDN RR
    +                       +                       +
    |                       |                       |
(1) | Request sent s123.ucdn.example.com            |
    +-----------------------+----------------------->
    |                       |                       |
(2) | Redirect to us-east1.dcdn.example.com         |
    <-----------------------+-----------------------+
    |                       |                       |
(3) | Request us-east1.dcdn.example.com             |
    +----------------------->                       |
    |                       |                       |
(4) | Response              |                       |
    <-----------------------+                       |
    |                       |                       |
    +                       +                       +