When configuring BGP on Cisco IOS XR Software, which address-family is enabled by default?

A.
IPv4 unicast

B.
IPv6 unicast

C.
VPNv4

D.
IPv4 unicast and IPv6 unicast

E.
IPv4 unicast and IPv6 unicast and VPNv4

F.
No address-family is enabled by default.

Explanation:

http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.8/routing/command/reference/rr38bgp.pdf
An address family must be explicitly configured in the router configuration mode for the address
family to be active in BGP. Similarly, an address family must be configured under the neighbor for
the BGP session to be established for that address family. An address family must be configured
in router configuration mode before it can be configured under a neighbor.