In RSTP, a port in the discarding state neither forwards data frames nor learns MAC addresses. A port in the learning state does not forward data frames but starts learning MAC addresses. Therefore, options A and B are correct, while C and D are incorrect due to misunderstandings of these states .

Comprehensive and Detailed In-Depth Explanation:
* IP Prefix lists are used to filter routes based on prefix and mask length.
* The optional parameters include:
* Index of the prefix list # Specifies priority/order (Optional).
* Shortest mask length to be matched # Defines the minimum subnet mask (Optional).
* Longest mask length to be matched # Defines the maximum subnet mask (Optional).
* Mask length (D) is mandatory because it specifies the exact prefix length being matched.
# Reference: Huawei HCIA-Datacom Study Guide, Configuring Prefix Lists for Route Filtering.

In IS-IS:
Level-1 routerscan only form neighbor relationships with other Level-1 routersin the same area.
Level-2 routerscan form neighbor relationships with other Level-2 routersregardless of area ID.
Level-1-2 routerscan form relationships at both levels depending on the peer's configuration.
So, iftwo Level-1 routershavedifferent area addresses, theycannotestablish a neighbor relationship.
Reference from Huawei HCIP-Datacom-Core Technology Study Guide:
"Level-1 routers must have the same area address to establish neighbor relationships. Level-2 routers can peer across different areas." (Chapter: IS-IS Protocol Principles - Section: Neighbor Establishment)

Comprehensive and Detailed Step-by-Step Explanation:
* STP and RSTP Behavior:
* STP: Only the designated port processes inferior BPDUs. Inferior BPDUs are received from downstream switches and typically indicate topology changes.
* RSTP: All ports, regardless of role (root, designated, or alternate), process inferior BPDUs to ensure faster convergence.
* Behavior Difference:
* RSTP improves convergence by allowing any port to process inferior BPDUs, unlike STP, which restricts this function to designated ports.
References:
* HCIA-Datacom Study Guide, Chapter: STP vs RSTP
Huawei STP and RSTP Configuration Comparison

Internet- Thiscommunity attribute allows a route to be advertised to any BGP peer, including EBGP and IBGP. This is the default behavior if no other restrictive community is attached.
No_Advertise- Prevents the route from being advertised toanypeer.
No_Export- Prevents the route from being advertised toEBGP peers.
No_Export_Subconfed- Restricts the route from being advertisedoutside the sub-ASin a confederation.
Reference from Huawei HCIP-Datacom-Core Technology Study Guide:
"The Internet community attribute allows unrestricted advertisement of a route. Other community attributes like No_Advertise and No_Export limit route propagation." (Chapter: BGP Community Attributes - Section: Well-known Communities)