Which of the following CHAP Authentication mechanisms is available when using software iSCSI, but not Hardware iSCSI?

A.
Mutual CHAP

B.
One-way CHAP

C.
Per-Subnet CHAP

D.
Per-Target CHAP

Explanation:

Software iSCSI support BOTH Per-Target and Mutual CHAP.
For Softare iSCSI only, you can set one-way CHAP and mutual CHAP for each initiator or at the target level.
Hardware iSCSI support CHAP only at the initiator level.

iSCSI SAN Configuration Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 37.

ESX/ESXi supports CHAP authentication at the adapter level. In this case, all targets receive the same CHAP name and secret from the iSCSI initiator. For software iSCSI, ESX/ESXi also supports per-target CHAP authentication, which allows you to configure
different credentials for each target to achieve greater level of security.

If in above question, choose two then you can select option D viz. Per-Target chap too.