Selective QinQ can add different outer tags to different inner packets.

Selective QinQ is used to add outer VLAN tags to customer (inner-tagged) packets, enabling service identification and isolation in carrier networks.

✅ B – Supported: You can match on inner VLAN IDs to apply different outer VLAN tags.

✅ C – Supported: 802.1p priorities (inner VLAN CoS values) can be used as match criteria.

✅ D – Supported: You can apply QinQ behavior based on QoS policies using traffic classification.

❌ A is false – Selective QinQ does not use TTL (Time To Live) as a matching criterion. TTL is an IP-layer field and not used in L2 QinQ configurations.

✅ Official Reference from Huawei:

" Selective QinQ allows different outer VLAN tags to be added based on inner VLAN IDs, 802.1p priorities, and QoS policy rules. TTL values are not used as matching conditions. "

— [Huawei HCIA-Datacom Certification Guide – VLAN and QinQ Chapter]