3.1.5.4 Receiving a DHCPv6 Reply Message
When a DHCPv6 client implementing this specification receives a Reply message that contains one or more User Class Options (Option 15), it MUST first check whether the option conforms to the syntax specified in section 2.2.4. If the option does not conform to the syntax, the DHCPv6 client MUST silently discard the option. Otherwise, the DHCPv6 client uses the information in an implementation-specific manner.