What is the subnet ID for the IPv6 address 2001:DA48:FC5:A4:3D1B::1/64?

The correct choice identifies the subnet ID for the provided IPv6 address. In IPv6 addressing, the subnet ID is derived from the first 64 bits of the address.

Given the address 2001:DA48:FC5:A4:3D1B::1/64, the first 64 bits are 2001:DA48:FC5:A4, which is the significant part of the address used to identify the subnet. The double colons (::) indicate the presence of one or more groups of zeros that can be omitted to simplify the address representation.

When the address is expressed as 2001:DA48:FC5:A4::/64, it maintains the necessary subnet identifier while eliminating the new host part and presenting a valid subnet format. This shows that the choice indicating 2001:DA48:FC5:A4::/64 accurately represents the subnet ID based on the /64 prefix length, which is standard for many IPv6 networks.

Other choices either provide incorrect subnetting or misinterpret the relevant bits of the IPv6 address for this specific subnet. For example, the choice that specifies the subnet ID but omits necessary sections of the address does not meet the requirements of the /64