A Totally Stubby Area in OSPF is a special type of stub area where only intra-area (Type 1) LSAs, router LSAs, and default routes (Type 3 LSA with 0.0.0.0/0) are allowed to be injected. It blocks inter-area routes (Type 3 LSAs for specific prefixes) and Type 5 LSAs (external routes) to reduce the size of the Link-State Database (LSDB) and enhance router performance.
Explanation of the Options:
* A. Type 3 specific LSA - # Correct Answer. These LSAs represent inter-area routes. Totally Stubby Areas do not allow Type 3 LSAs for specific routes, only for the default route (0.0.0.0/0).
* B. Type 1 LSA - # Allowed. These are Router LSAs generated by routers within the area and are necessary for OSPF to function.
* C. Type 3 LSA that describes a default route - # Allowed. This is the only Type 3 LSA permitted in a Totally Stubby Area. It provides a default route (0.0.0.0/0) to reach external destinations.
* D. Type 2 LSA - # Allowed if there are broadcast or NBMA networks in the area. These describe the network segment in multi-access environments and are generated by the DR.
Official Huawei Reference:
# Huawei HCIP-Datacom-Core Technology Study Guide -
Chapter: OSPF Special Areas
* "A totally stub area does not allow inter-area Type 3 LSAs or external Type 5 LSAs to enter. Only a default route is injected in the form of a Type 3 LSA (0.0.0.0/0), which greatly reduces the LSDB size."
# Also refer to:
* Huawei VRP Command Guide > OSPF > Configuration Notes > OSPF Special Areas

ARP spoofing is a Layer 2 attack, as it targets ARP tables in switches or end devices. All other attacks, including IP spoofing, ICMP attacks, and Smurf attacks, are network layer (Layer 3) attacks .

Comprehensive and Detailed Step-by-Step Explanation:
DHCP Configuration Issues:
Option C:The DHCP function isdisabled by defaulton Huawei devices. If the administrator forgets to enable it, clients cannot receive IP addresses.
Option D:DHCP uses broadcast messages, which do not traverse routers. If the clients and DHCP server are on different subnets, aDHCP relay agentmust be configured.
Other Options:
Option A:Multiple DHCP servers can coexist as long as their IP address pools do not overlap. This is unlikely to cause the problem.
Option B:STP does not affect DHCP operations unless it delays port activation, which is uncommon in this scenario.
References:
HCIA-Datacom Study Guide, Chapter: DHCP Configuration and Troubleshooting Huawei DHCP Relay Agent Configuration

Apseudonodein IS-IS is a logical representation of a broadcast network segment (e.g., Ethernet) where theDesignated Intermediate System (DIS)generates an LSP on behalf of the LAN.
Pseudonode LSPs contain:
Interface information(i.e., the interface that connects to the pseudonode) Neighbor information(adjacencies with other routers on the LAN) Protocol information(e.g., supported address families) However,route information is not containedin LSPs generated by pseudonodes because routing information is advertised in theLSPs generated by the routers themselves, not the pseudonode.
Reference from Huawei HCIP-Datacom-Core Technology Study Guide:
"Pseudonode LSPs contain information about the broadcast link, including interface and neighbor data. They do not advertise routing entries." (Chapter: IS-IS Advanced Features - Section: DIS and Pseudonodes)

Comprehensive and Detailed In-Depth Explanation:
When a packet is checked against anAccess Control List (ACL), it is processed based on rule matches.
"Unmatched" scenariosoccur if:
A: TRUE# The packetdoes not match any ACL rule.
C: TRUE#No ACL is configured, so there are no rules to match.
D: TRUE#An empty ACL exists, meaning no rules are defined.
B is incorrectbecauseif the packet matches a deny rule, it is "matched" and explicitly dropped, not
"unmatched".
#Reference:Huawei HCIA-Datacom Study Guide, ACL Rule Matching and Processing Logic.