Which two options are storage topologies? (Choose two.)

A.
WAS

B.
DAS

C.
CAS

D.
NAS

Explanation:
Direct Attached Storage (DAS)
DAS is the traditional method of locally attaching storage devices to servers via a direct communication path between the server and storage devices. As shown in
Figure 1, the connectivity between the server and the storage devices are on a dedicated path separate from the network cabling. Access is provided via an
intelligent controller. The storage can only be accessed through the directly attached server. This method was developed primarily to address shortcomings in drivebays on the host computer systems. When a server needed more drive space, a storage unit was attached. This method also allowed for one server to mirror
another. The mirroring functionality may also be accomplished via directly attached server to server interfaces.

Network Attached Storage (NAS)
NAS is a file-level access storage architecture with storage elements attached directly to a LAN. It provides file access to het erogeneous computer systems. Unlike
other storage systems the storage is accessed directly via the network as shown in Figure 2. An additional layer is added to address the shared storage files. This
system typically uses NFS (Network File System) or CIFS (Common Internet File System) both of which are IP applications. A separate computer usually acts as the
“filer” which is basically a traffic and security access controller for the storage which may be incorporated into the unit itself. The advantage to this method is that
several servers can share storage on a separate unit. Unlike DAS, each server does not need its own dedicated storage which enables more efficient utilization of
available storage capacity. The servers can be dif ferent platforms as long as they all use the IP protocol.