Which objects will Sync-Only device groups actually sync?

So this is really not as complex as it sounds, but it's also not well documented. A Sync only device group only syncs non traffic objects. It won't sync Virtual Servers, Pools, Floating IPs, etc, but it will sync your APM objects and your ASM policies.

To illustrate how this can be helpful, consider a situation where you have a data center in Denver, and one in Fort Lauderdale. Same configuration, same servers, different IP addressing.

Sync Only allows your ASMs to be centrally managed while automatically protecting both data centers.

Sync-Failover allows for on site redundancy.