Free Huawei H12-821_V1.0 Practice Exam with Questions & Answers

IPv4 supports three main transmission modes:

Unicast: One-to-one communication.

Broadcast: One-to-all communication within a network.

Multicast: One-to-many communication to a group of interested receivers.Anycast is not a native IPv4 mode but is introduced in IPv6 ​.

The Origin attribute in the display bgp routing-table output is marked as i, indicating that the route was injected into the BGP routing table using the network command. The other options are incorrect because the AS path is not displayed, the MED is 0, and the route is marked as the best ( > ), meaning it is the optimal route ​.

DIS Election in IS-IS:

In IS-IS, the Designated Intermediate System (DIS) is elected on broadcast networks to reduce the number of LSAs exchanged and maintain the LSDB.

The DIS is elected based on priority:

The router with the highest priority is elected as the DIS.

If priorities are equal, the System ID is used as a tie-breaker, and the router with the highest System ID becomes the DIS.

HCIP-Datacom-Core Technology Training Material (IS-IS DIS Election Mechanism)​​.

Given DIS Priorities:

R1: Priority = 10

R2: Priority = 20

R3: Priority = 30

R4: Priority = 40

R4 has the highest DIS priority of 40, which makes it the clear choice for DIS election.

Scenario Details:

Since all devices are started simultaneously, the DIS election process will follow the priorities without requiring a tie-breaker (System ID).

Conclusion:

The device with the highest DIS priority is R4, and it will be elected as the DIS.

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding LSA Filtering in OSPF and IS-IS:

The filter-policy command is used in OSPF and IS-IS to control which routing information is imported into the local routing table or advertised to other neighbors.

However, it cannot filter LSAs forwarded by neighbors. In OSPF and IS-IS, LSAs are always forwarded unchanged within the area to ensure all routers have a consistent link-state database.

Filtering only affects the routes that are installed into the local routing table or advertised to other areas or neighbors.

2. Why the Statement is False:

LSAs are forwarded without being filtered. This ensures link-state protocols maintain the same network topology view across the network.

The filter-policy import command only controls routes that are installed into the local routing table, not the forwarding of LSAs.

3. Summary:

The statement is FALSE because LSAs cannot be filtered by filter-policy import.

Huawei HCIA-Datacom Study Guide, Chapter "OSPF Route Filtering."

RFC 2328: OSPF Version 2, LSA Propagation Rules.

BGP, IS-IS, and OSPF support the configuration of default routes through specific command configurations. For example, BGP uses the default-originate command, IS-IS uses a default-route-advertise method, and OSPF can advertise default routes using default-information originate. ICMP, however, is not a routing protocol and does not support this functionality ​.

Goal Analysis:

Requirement:

The route to 192.168.3.0/24 must exist in R1's and R3's routing tables.

The route must not exist in R2's routing table.

This requires filtering to ensure the route is either:

Blocked on R2's routing table (via filtering on R2), or

Blocked before it is advertised to R2.

Analysis of Each Option:

Option A (Filter-policy on R2 for filtering received routes):

Applying a filter-policy on R2 to filter received routes will block the route from entering R2's routing table but still allow it to propagate to R3.

This meets the requirement.

Option B (Filter-policy on R2 for filtering the routes to be advertised):

Blocking the advertisement of routes from R2 to other routers does not affect the routes received by R2 itself.

This does not meet the requirement but does not affect the propagation to R3.

This is valid if the received route is blocked.

Option C (Filter-policy on R1 for filtering the routes to be imported):

If the route is filtered on R1 during the import phase, the route will not exist in R1’s routing table and thus cannot be advertised to either R2 or R3.

This fails to meet the requirement because the route must exist in R1's and R3's routing tables.

Option D (Filter-policy on R1 for filtering the imported routes to be advertised):

Filtering routes on R1 before advertising to R2 will prevent R2 from receiving the route but allow R1 to advertise the route to R3.

This meets the requirement.

Correct Option:

C (Filter-policy on R1 for filtering the routes to be imported): This will prevent the route from existing in both R1 and R3, violating the stated requirement.

Comprehensive and Detailed Step-by-Step Explanation:

1. IPv6 and Neighbor Discovery Protocol (NDP):

In IPv4, a host uses ARP (Address Resolution Protocol) to map an IP address to a MAC address for communication.

In IPv6, ARP is not used. Instead, IPv6 uses the Neighbor Discovery Protocol (NDP) for address resolution.

2. Why the Statement is FALSE:

IPv6 does not use ARP for resolving link-layer addresses.

IPv6 uses NDP, which operates through ICMPv6 messages to perform the equivalent function.

3. Summary:

The statement is FALSE because IPv6 uses NDP, not ARP, to obtain the link-layer address of the destination host.

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of BGP:

BGP (Border Gateway Protocol) is an Exterior Gateway Protocol (EGP) designed to exchange routing information between different Autonomous Systems (ASs) on the internet. Unlike traditional distance-vector protocols (like RIP), BGP is considered a path-vector protocol, as it not only determines reachability but also ensures policy-based routing decisions and advanced path selection mechanisms.

2. Analysis of Each Option:

Option A: BGP does not support authentication. Therefore, it cannot ensure network security.

This statement is incorrect.

BGP supports authentication using mechanisms such as TCP MD5 (Message Digest 5) and TCP-AO (Authentication Option). These authentication mechanisms ensure that BGP messages are not tampered with or intercepted during transmission, enhancing network security.

HCIA-Datacom Study Guide, Chapter "BGP Concepts and Features," Authentication Section.

Option B: BGP uses TCP as the transport layer protocol.

This statement is correct.

BGP relies on TCP (Transmission Control Protocol) as its transport layer protocol, specifically on port 179. TCP provides reliable delivery of BGP messages and ensures the session remains established in case of transient network issues.

TCP also handles error recovery and sequencing, making it a suitable choice for BGP, which requires reliable communication between peers.

Comprehensive and Detailed Step-by-Step Explanation:

HSB (Hot Standby Backup) Service:

HSB is used on WLAN controllers to back up critical information in real time to a backup device, ensuring service continuity in case of failures.

Backed-Up Information:

CAPWAP Tunnel Information (A): Essential for maintaining connections between APs and controllers.

AP Entries (C): Information about connected APs is backed up.

User Data Information (D): Includes client authentication and session details.

Incorrect Option:

DHCP Address Information (B): Not part of HSB's responsibilities, as DHCP is handled separately.