Now that the client-side details have been mentioned, you may be interested in the specifics of the client/server bootstrap interactions. The actual setup of this aspect of things is now primarily handled by installadm, covered a little further on.
Keep in mind that the initial bootstrap process for network installation for SPARC versus x86 is still very different for each architecture. The backend configuration is new, but still unified for both of them. However, a summary of each follows.
SPARC still uses wanboot at the lowest level. The official Oracle method says that you must use DHCP boot, but whether you boot from media, or directly from network, it still basically just hooks into wanboot as its first stage.
The additional benefit from booting the first stage through DHCP is that it picks up DNS information. In theory, they could have made it pick up DNS from other means, but they have not chosen to do that at this time. This is...