What link costs are

Link costs let you prioritize which data center site provides a requested service when two or more data center sites exist.

You can configure link costs to control how API Gateway Nodes direct traffic, and which replicated copy of an object is used to fulfill a retrieval.

Conceptual diagram for link costs between data centers
Link costs are arbitrary relative numbers with no specific unit of measure. For example, a link cost of 50 is used less preferentially than a link cost of 25. The table shows commonly used link costs.
Link Link cost Notes
Between physical data center sites 25 (default) Data centers connected by a WAN link.
Between logical data center sites at the same physical location 0 Logical data centers in the same physical building or campus connected by a LAN.