What Cisco IOS (Internetwork Operating System) command enables stateless DHCPv6 (Dynamic Host Configuration Protocol version 6) on a router interface, and what does it change?

ipv6 nd other-config-flag — it sets the O flag to 1 in RA (Router Advertisement) messages, telling hosts to contact a DHCPv6 server for additional configuration.

Configuration:

R1(config)# interface g0/0/1
R1(config-if)# ipv6 nd other-config-flag

What this changes in the RA:

• A flag remains 1 (hosts still use SLAAC (Stateless Address Autoconfiguration) for addressing)
• O flag changes from 0 to 1 (hosts should get other config from DHCPv6)
• M flag remains 0 (hosts do NOT get addresses from DHCPv6)

Verification:

R1# show ipv6 interface g0/0/1 | begin ND

Look for:

• Hosts use stateless autoconfig for addresses.
• Hosts use DHCP to obtain other configuration.

To reset back to SLAAC only:

R1(config-if)# no ipv6 nd other-config-flag

Go deeper:

• RFC 4861 — RA M and O flags — the Other-config (O) flag bit ipv6 nd other-config-flag sets in the RA.