Free Practice Questions for Huawei H12-821_V1.0 Exam

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:

Session Creation in Firewalls:

Firewalls create session entries for packets requiring stateful inspection (e.g., TCP, UDP, ICMP, and GRE).

Subsequent fragments of large packets do not require new sessions. Instead, they are processed based on the session created for the first fragment.

Correct Option:

C (Subsequent Fragment): Does not trigger a new session entry as it belongs to an existing session.

Multi-channel protocols such as H.323 and FTP use separate control and data channels. H.323 uses different channels for call signaling and media streaming, while FTP uses a control channel for commands and a data channel for file transfers. Telnet and SMTP are single-channel protocols ​.

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.

In OSPF (Open Shortest Path First), each router maintains a Link-State Database (LSDB), which must be synchronized with other routers in the same area. When an OSPF router receives an LSA (Link-State Advertisement) that it does not already have in its LSDB, it takes the following steps:

It updates its LSDB with the new LSA.

It floods the LSA to all its other OSPF neighbors (except the one from which it received the LSA).

This ensures that all routers in the OSPF area eventually converge to the same network topology.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“When an LSA is received and it is newer or not present in the LSDB, the router updates the LSDB and floods the LSA to other neighbors to ensure database synchronization.”

(Chapter: OSPF Fundamentals – Section: LSDB Synchronization)

An OSPF AS-external LSA is used to describe routes to networks that are external to the OSPF Autonomous System (AS). This external route information is typically imported into OSPF by an Autonomous System Boundary Router (ASBR).

If the Forwarding Address field in the AS-external LSA is set to 0.0.0.0, this indicates that traffic destined for the external network should be forwarded directly to the ASBR that advertised the external route.

The specific context mentioned here relates to the Not-So-Stubby Area (NSSA), a type of OSPF area designed to handle AS-external routes in a more controlled way. In NSSAs:

Type 7 LSAs are used to describe AS-external routes.

The ASBR within the NSSA converts the Type 7 LSA to a Type 5 LSA before advertising it to the backbone area.

Hence, the correct acronym for the described functionality is NSSA.

The Designated Intermediate System (DIS) in an IS-IS broadcast network sends Complete Sequence Number PDUs (CSNPs) at a default interval of 30 seconds. This interval ensures periodic synchronization of the Link State Database (LSDB) among IS-IS neighbors ​.

In OSPF, DR and BDR listen on the multicast address 224.0.0.6, while all OSPF routers (including DR others) listen on 224.0.0.5. DR others establish neighbor relationships with DR and BDR, but they do not listen on 224.0.0.6. This makes Option D incorrect, as only DR and BDR use 224.0.0.6 ​.