A PPPoE client obtains DNS and NBNS name servers by including following configuration options in its IPCP Configure Request:
Primary DNS Server Address (129)
Primary NBNS Server Address (130)
Secondary DNS Server Address (131)
Secondary NBNS Server Address (132)
Note: A PPPoE DHCPv4 client does not include a Parameter Request List Option (55) in its DHCP
messages. The Domain Name Server Option (6), the NetBIOS Name
Server Option (44), or both that is returned by the DHCP server
are evaluated according to the authentication origin priority to
determine the DNS and NBNS name server IP address assigned to
the PPPoE session.
Mid-session changes are not supported for PPPoE DNSv4 and NBNS name server updates.