The Climatological Data Land Model (dlnd) functions as the land component in a CCSM configuration. Recall that a configuration consists of various independent component models (atmosphere, sea-ice, land, and ocean), each connected to a coupler. The dlnd land component interacts with the coupler just like any land model would, but it is not an active model, rather, it takes land data from an input data file and sends it to the coupler, ignoring any forcing data received from the coupler. Typically the input data file contains mean monthly data generated by an active CCSM land model (it's unlikely that real world observations exist for all the required fields). Such a "dummy" land model is useful for doing ocean + ice spinup runs.
Important note: When assembling a CCSM configuration, the user must carefully consider the limitations and requirements of all components and make sure that the complete set of component models will interact in a meaningful way. In particular, the user must verify that the data provided by this model is adequate for their specific application.