H12-821_V1.0 Exam Dumps - Huawei HCIP-Datacom Questions and Answers

Comprehensive and Detailed Step-by-Step Explanation:

Packet Filtering Firewall:

A packet filtering firewall inspects packets at the network and transport layers based on predefined rules (e.g., ACLs).

Correct Statements:

Option B:Packet filtering is performed on a per-packet basis.

Option D:ACLs define the filtering rules for traffic.

Incorrect Statements:

Option A:Packet filtering firewalls do not analyze associated packets. For this, a stateful firewall is required.

Option C:Application-layer inspection is not supported. This functionality is provided by application-layer firewalls.

Comprehensive and Detailed In-Depth Explanation:

Wireless LAN (WLAN) roamingallows mobile devices (STAs) to moveseamlessly between different APswithoutdropping connections.

Types of WLAN Roaming:

Layer 2 roaming→ STAs move between APs in thesame subnetwithout IP address changes.

Layer 3 roaming→ STAs move acrossdifferent subnets, requiringIP address reconfiguration(handled via DHCP or tunneling).

Since roamingprevents service interruptionin large WLAN deployments, the statement istrue.

????Reference:Huawei HCIA-Datacom Study Guide, WLAN Roaming and Seamless Connectivity.

When the level of an IS-IS interface is changed, the adjacency must be re-established because IS-IS adjacencies are formed based on matching levels (Level-1, Level-2, or both). Other changes, such as cost or hello intervals, do not disrupt the existing adjacency but might impact routing metrics or timing ​.

Comprehensive and Detailed In-Depth Explanation:

IPsec (IP Security Protocol)establishesSecurity Associations (SAs)for encrypted communication.

AnSA is uniquely identified by a 3-tuple:

SPI (Security Parameter Index)→ Identifies the SA.

Destination IP Address→ Specifies the receiving device.

Security Protocol ID→ Indicates whetherAH (Authentication Header) or ESP (Encapsulating Security Payload)is used.

A. Key exchange protocolisnotpart of theSA 3-tuple. It is used duringIKE (Internet Key Exchange)but is not part of the SA itself.

????Reference:Huawei HCIA-Datacom Study Guide, IPsec Security Association and SA Identification.

Policy-Based Routing (PBR) on interfaces is used to forward traffic based on specific policies rather than the routing table. However, PBR is not suitable for modifying the next-hop of locally originated traffic. Other scenarios listed are typical use cases for interface PBR ​.

When routes are imported into BGP using theimport-routecommand, the origin attribute is set toincompleteby default. This indicates that the route's origin is not known or is from an external source, as opposed to being explicitly learned through an IGP (IGP) or EGP (EGP) protocol ​.

Comprehensive and Detailed in-depth Step-by-Step Explanation:

In IS-IS, theinterface costis a metric used to determine the best path to a destination. Lower-cost paths are preferred over higher-cost paths. By default, IS-IS interface costs can range from1 to 63.

Default Cost Range:

IS-IS allows the configuration of interface costs within the range of1–63by default. This range is sufficient for most networks.

Maximum Configurable Cost:

The maximum value that can be configured by default is63. If there is a requirement for a higher cost range, the metric-style can be changed towide, which allows the cost range to extend beyond 63.

Option A (67):Incorrect. 67 is not the maximum default value.

Option B (63):Correct. This is the maximum default cost value.

Option C (64):Incorrect. This is beyond the default range.

Option D (68):Incorrect. This is beyond the default range.

 Inasynchronous mode, BFD control packets are exchanged periodically to detect faults.

 Indemand mode, once the session is established, BFD stops sending periodic control packets and relies on external mechanisms to verify connectivity.

 Asynchronous mode is the most commonly used mode. However, the Echo function is supported in asynchronous mode, making Option B incorrect ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is GRE (Generic Routing Encapsulation)?

GRE is a tunneling protocol that allows the encapsulation of various types of packets (e.g., IPv4, IPv6, multicast, etc.) to be transmitted over another protocol (e.g., IP).

GRE is used to create point-to-point connections over heterogeneous networks.

2. Analysis of Each Option:

Option A: GRE is a Layer 2 VPN encapsulation technology.

Incorrect.

GRE operates at Layer 3 (Network Layer) and encapsulates Layer 3 packets. It is not a Layer 2 VPN encapsulation technology like MPLS or Ethernet-over-IP.

Option B: GRE enables encapsulated data packets to be transmitted over another network layer protocol, but cannot encapsulate multicast data.

Incorrect.

GRE supports the encapsulation and transmission of multicast data packets. This is one of its key features, making it suitable for protocols like OSPF and multicast applications.

Option C: GRE tunnels can work with IPsec to ensure the security of multicast services such as voice and video.

Correct.

GRE by itself does not provide encryption or security. However, GRE can work with IPsec to secure the encapsulated traffic, including multicast data, for services like voice and video.

Option D: GRE tunnels can extend the working range of network protocols with hop limits.

Correct.

GRE encapsulates packets, effectively resetting their hop limits and allowing protocols with limited hop counts (e.g., RIP) to work over larger networks.

3. Summary:

The correct options areCandD.

In a stateful inspection firewall, if the status detection mechanism is enabled, it tracks and validates the state of connections using the session table. If there is no session table and a SYN+ACK packet reaches the firewall, it checks the security policy. If the policy explicitly permits the packet, it will pass through the firewall, but no session table will be created without the initial SYN packet. The other options are either incorrect or misrepresent the behavior of stateful inspection ​.