View Full Huawei H12-821 Exam Dumps and Practice Test Dumps.

Question 341. What is the PRIMARY purpose of Network Address Translation (NAT) in an enterprise IPv4 network?

1. To replace IP routing protocols
2. To translate IP address information so private-network hosts can communicate with public networks or published services
3. To create Ethernet spanning trees
4. To assign VLAN IDs dynamically

Correct Answer: 2. To translate IP address information so private-network hosts can communicate with public networks or published services

Explanation:

NAT translates addressing information in IP packets as traffic crosses between address domains. A common enterprise use is translating private IPv4 source addresses into public IPv4 addresses so internal users can access the Internet. NAT can also publish internal servers by mapping public addresses or ports to private addresses and ports. Huawei supports several NAT methods, including dynamic NAT, Easy IP, PAT, and static/NAT Server mappings. NAT helps conserve public IPv4 address space and hides internal addressing, but it does not replace normal routing because the device still needs valid routes for packet forwarding.

Question 342. Which public IPv4 address does Huawei Easy IP normally use for source translation?

1. The DHCP server’s address
2. The destination server’s address
3. A randomly generated public address
4. The public IPv4 address configured or dynamically obtained on the outbound interface

Correct Answer: 4. The public IPv4 address configured or dynamically obtained on the outbound interface

Explanation:

Easy IP uses the public IPv4 address of the NAT device’s outbound interface as the translated source address. Because different internal sessions can be distinguished by translated transport-layer port numbers, many private hosts can share this single public address. Huawei specifically notes that Easy IP also works when the outbound interface receives its address dynamically, making the method suitable for broadband or other links where the public address may change. An administrator therefore does not need to maintain a fixed NAT address pool merely to support Internet access through one dynamically addressed WAN interface.

Question 343. How does dynamic NAT in address-pool mode obtain translated addresses for internal users?

1. It selects available public addresses from a configured NAT address pool as users create sessions
2. It always uses the destination server’s address
3. It assigns the same private address to every host
4. It requires a fixed one-to-one mapping for every user in advance

Correct Answer: 1. It selects available public addresses from a configured NAT address pool as users create sessions

Explanation:

In dynamic NAT address-pool mode, the NAT device maintains a configured set of public IPv4 addresses. When internal users initiate sessions toward public networks, available public addresses are selected from the pool according to the NAT implementation. Unlike static NAT, the private-to-public mapping is not necessarily predetermined permanently for each host. Huawei distinguishes address-pool mode from Easy IP, where the outbound interface address itself is used. Dynamic NAT is therefore well suited to organizations with a limited set of public addresses that must be shared dynamically among internal users accessing external services.

Question 344. Which Huawei NAT feature should normally be configured when Internet users need to initiate connections to an internal web server?

1. Easy IP only
2. DHCP snooping
3. NAT Server
4. uRPF

Correct Answer: 3. NAT Server

Explanation:

NAT server creates a fixed mapping that allows public-network users to reach a service hosted on a private internal network. The mapping can associate a public IP address and port with a private server address and service port. When an Internet client sends traffic to the public representation, the NAT device translates the destination information and forwards the packet toward the internal server. This is different from Easy IP, which is primarily designed for sessions initiated by internal users going outward. Huawei specifically identifies web and FTP publishing as typical NAT Server use cases.

Question 345. What is the PRIMARY benefit of PAT compared with simple one-to-one address translation?

1. PAT disables TCP and UDP ports
2. PAT requires one public IP address for every private host
3. PAT can only be used for server publishing
4. PAT allows multiple private sessions to share public IP addresses by also translating port numbers

Correct Answer: 4. PAT allows multiple private sessions to share public IP addresses by also translating port numbers

Explanation:

Port Address Translation conserves public IPv4 addresses by distinguishing sessions using translated port numbers as well as translated IP addresses. Several private hosts can therefore communicate with public services while sharing one or a small number of public IPv4 addresses. Huawei’s Easy IP mechanism also applies port translation while using the outbound interface’s public address, which is why a large number of private users can access the Internet through a single public interface address. The NAT device maintains session information so return traffic can be translated back to the correct internal host and original port.

Question 346. Which packet field is the main matching criterion available in a Huawei basic IPv4 ACL?

1. Destination TCP port only
2. Source IPv4 address
3. BGP AS_Path
4. Destination MAC address only

Correct Answer: 2. Source IPv4 address

Explanation:

A Huawei basic ACL is designed mainly to classify packets according to their source IPv4 addresses, along with applicable parameters such as VPN instance or time range on supported platforms. It is appropriate when policy needs only to distinguish where traffic originates. If filtering must consider destination addresses, IP protocols, TCP or UDP ports, DSCP values, or other Layer 3 and Layer 4 information, an advanced ACL is more suitable. Huawei normally uses ACL numbers 2000–2999 for basic IPv4 ACLs, while advanced IPv4 ACLs typically use numbers 3000–3999.

Question 347. Which requirement is BEST suited to a Huawei advanced ACL rather than a basic ACL?

1. Permit traffic from a specific source subnet to TCP destination port 443 while denying selected other traffic
2. Match routes only by destination prefix for route summarization
3. Elect an OSPF DR
4. Assign DHCP addresses

Correct Answer: 1. Permit traffic from a specific source subnet to TCP destination port 443 while denying selected other traffic

Explanation:

An advanced ACL supports more granular packet classification than a basic ACL. Huawei advanced ACL rules can match source and destination IP addresses, IP protocol types, TCP or UDP port numbers, DSCP values, TCP flags, and other supported fields. A policy that needs to distinguish HTTPS traffic from a particular source network therefore requires the richer matching capabilities of an advanced ACL. A basic ACL is generally limited mainly to source-address matching. Selecting the correct ACL type keeps the rule set understandable while providing enough detail to enforce the intended traffic policy.

Question 348. How are ACL rules normally evaluated when Huawei ACL rules use configuration-order matching?

1. The rule with the largest destination address is always selected
2. Every rule is applied to every packet
3. Rules are checked in order, and processing stops when the packet matches an applicable rule
4. Deny rules are always evaluated after all permit rules

Correct Answer: 3. Rules are checked in order, and processing stops when the packet matches an applicable rule

Explanation:

Huawei ACLs contain multiple permit or deny rules arranged according to the ACL’s matching order. With normal configuration-order processing, rules are examined in sequence, commonly according to their rule IDs. Once a packet matches a rule, the ACL returns that rule’s result to the feature using the ACL and does not continue searching lower rules for the same packet. Rule ordering is therefore critical. A broad rule placed before a more specific rule may capture traffic unexpectedly and prevent the later rule from ever being evaluated. Administrators should design ACL sequence numbers carefully for future rule insertion and maintenance.

Question 349. When an ACL is applied using Huawei traffic-filter and a packet matches none of the ACL rules, what is the documented behavior?

1. The unmatched packet is allowed to pass
2. The interface is shut down
3. The packet is automatically sent to the CPU
4. The packet is converted into multicast traffic

Correct Answer: 1. The unmatched packet is allowed to pass

Explanation:

For Huawei’s documented traffic-filter application, a packet matching an ACL deny rule is discarded, while a packet matching a permit rule is forwarded. Importantly, Huawei also documents that packets that match no ACL rule are allowed to pass for this feature. This illustrates an important exam concept: the meaning of unmatched traffic can depend on the service that references the ACL. Administrators should not assume that every ACL usage has exactly the same implicit behavior. The ACL supplies classification results, while the referencing feature determines how those results affect packets or routes.

Question 350. How many ACLs can normally be directly applied by traffic-filter in one direction on a Huawei interface according to the documented restriction?

1. Unlimited ACLs
2. Four ACLs
3. Two ACLs
4. One ACL

Correct Answer: 4. One ACL

Explanation:

Huawei documentation for the interface traffic-filter feature states that only one ACL can be applied in a particular direction on an interface for packet filtering. The direction can be inbound or outbound. If policy becomes more complex, administrators should generally consolidate the required filtering logic into the referenced ACL or use an appropriate traffic-policy framework rather than expecting to attach multiple independent traffic-filter ACLs in the same direction. Understanding this restriction helps prevent configuration attempts that cannot be accepted or that unexpectedly replace an existing policy.

Question 351. What happens when a packet matches a deny ACL rule referenced by traffic-filter?

1. The packet is marked with a higher DSCP value
2. The packet is forwarded normally
3. The packet is discarded
4. The packet becomes an OSPF packet

Correct Answer: 3. The packet is discarded

Explanation:

When a Huawei ACL is referenced by the traffic-filter feature, a matching deny rule causes the device to discard that packet. A matching permit rule allows the packet to continue forwarding. This makes ACL-based traffic filtering a straightforward mechanism for restricting unwanted traffic on an inbound or outbound interface. Administrators should still consider rule order and the documented treatment of unmatched traffic, because a rule that is too broad can deny legitimate services or allow traffic before a more specific rule is reached. Careful testing is recommended before applying restrictive ACLs to production interfaces.

Question 352. What does a matching permit rule do when the ACL is being used by Huawei traffic-filter?

1. It shuts down the interface
2. It allows the matching packet to be forwarded
3. It forces NAT translation
4. It deletes the route to the destination

Correct Answer: 2. It allows the matching packet to be forwarded

Explanation:

In the context of interface traffic-filter, Huawei defines a permit ACL result as allowing the matching packet to pass. The ACL identifies which packets match the configured conditions, and the traffic-filter service applies the filtering action. This context matters because the same ACL action can have a different operational interpretation when the ACL is referenced by another feature. For example, a NAT policy may use a permit rule to identify traffic that should undergo translation rather than simply to decide whether the packet is forwarded. Understanding both the ACL and the feature consuming it is therefore essential.

Question 353. When an ACL is referenced by Huawei dynamic NAT, what does a matching permit rule indicate?

1. The packet must be dropped
2. The packet must bypass routing
3. The ACL automatically publishes an internal server
4. The matching source traffic is eligible for the configured NAT translation

Correct Answer: 4. The matching source traffic is eligible for the configured NAT translation

Explanation:

When a basic or advanced ACL is used by Huawei dynamic NAT, a permit rule identifies the traffic whose source address should undergo the configured translation. Huawei documentation explains that packets whose source matches a permitted ACL rule can use the configured NAT address pool. If the required permit condition is not met, the NAT policy does not perform translation for that traffic; normal routing processing can still occur. This is a good example of why ACL behavior must be interpreted in the context of the feature referencing it rather than assuming permit and deny always mean only simple packet forwarding and dropping.

Question 354. Why might existing NAT sessions need to be cleared after changing an ACL referenced by a Huawei NAT policy?

1. Existing translation mappings may continue using previously created session information until the NAT session entries are refreshed
2. ACL changes automatically disable IP routing
3. NAT ACLs can never be modified
4. The router must always be rebooted after an ACL change

Correct Answer: 1. Existing translation mappings may continue using previously created session information until the NAT session entries are refreshed

Explanation:

NAT is stateful and maintains mapping or session entries for active connections. Huawei warns that changing an ACL already referenced by NAT may not immediately alter existing translation behavior because current NAT sessions were created using the previous policy conditions. Huawei documentation recommends clearing the relevant NAT mapping/session information when immediate application of the revised ACL is necessary. This should be done carefully because clearing sessions can interrupt active connections. The concept illustrates the distinction between changing a policy definition and changing state that has already been created under the old policy.

Question 355. What is the PRIMARY purpose of DHCP Option 82?

1. To carry a client’s DNS password
2. To record information about the client’s attachment location so the DHCP server can apply location-aware address or security policies
3. To replace the DHCP ACK message
4. To encrypt DHCP traffic

Correct Answer: 2. To record information about the client’s attachment location so the DHCP server can apply location-aware address or security policies

Explanation:

DHCP Option 82 is the Relay Agent Information Option. A DHCP relay agent or DHCP snooping-enabled access device can insert it into a client’s DHCP request to describe where the client is attached. The DHCP server can then use that information when selecting address pools or applying access policies. This provides more control than treating every DHCP client in the same broadcast domain identically. Huawei notes that Option 82 primarily records location information; the DHCP server must itself support Option 82 and have suitable policies configured if that information is to influence address allocation or security decisions.

Question 356. What does the DHCP Option 82 Circuit ID commonly identify?

1. The DHCP server’s routing protocol
2. The client’s operating system
3. Attachment information such as the VLAN ID and interface through which the client connects
4. The public NAT address

Correct Answer: 3. Attachment information such as the VLAN ID and interface through which the client connects

Explanation:

Huawei describes Circuit ID as one of the commonly used Option 82 suboptions. It identifies information about the circuit through which the DHCP client reaches the relay or snooping device, such as the VLAN and interface associated with that endpoint. This allows the DHCP server to distinguish clients based not only on their DHCP messages but also on their physical or logical access locations. A provider or enterprise can then assign different address pools or policies to clients connected through different ports or VLANs, assuming the DHCP server is configured to interpret the Option 82 information.

Question 357. What does the DHCP Option 82 Remote ID commonly distinguish in Huawei’s described implementation?

1. The device to which the client is connected, commonly using identifying information such as its MAC address
2. The client’s TCP destination port
3. The OSPF area number
4. The NAT translation port

Correct Answer: 2. The device to which the client is connected, commonly using identifying information such as its MAC address

Explanation:

The Remote ID is another commonly used Option 82 suboption. Huawei describes it as information used to distinguish the access device associated with the client, with the device MAC address commonly used as identifying information. Combined with Circuit ID, the DHCP server can learn both which device and which circuit or port a client is using. This can support detailed address-allocation and security policy. Option 82 does not replace the client’s normal MAC address or DHCP transaction information; it supplements the DHCP request with trusted relay-side context about the client’s network attachment.

Question 358. What must be true for a DHCP server to allocate addresses differently based on Option 82 information?

1. The switch must run BGP
2. The client must configure a public address first
3. NAT Server must be enabled
4. The DHCP server must support Option 82 and have suitable address-allocation or security policies configured

Correct Answer: 4. The DHCP server must support Option 82 and have suitable address-allocation or security policies configured

Explanation:

Inserting Option 82 into DHCP requests does not automatically cause the server to make different address decisions. Huawei explicitly states that the DHCP server must understand the Option 82 field and be configured with appropriate allocation or security policies. Once configured, the server can use information such as Circuit ID, Remote ID, or supported link-selection information to choose the correct address pool or policy for the client’s location. This separation is important: the relay or snooping device supplies trustworthy location metadata, while the DHCP server ultimately decides how that metadata influences address assignment.

Question 359. How does a DHCP snooping binding entry differ from DHCP Option 82?

1. They are exactly the same structure created at the same time
2. A snooping binding exists before the client requests an address
3. Option 82 is added to DHCP requests to describe client location, whereas a snooping binding is created after DHCP assignment information such as the ACK is observed
4. Option 82 is used only for IPv6 routing

Correct Answer: 3. Option 82 is added to DHCP requests to describe client location, whereas a snooping binding is created after DHCP assignment information such as the ACK is observed

Explanation:

Option 82 and the DHCP snooping binding table serve related but different purposes. Option 82 is inserted into a DHCP request before the client has received an address and communicates attachment-location information to the DHCP server. A DHCP snooping binding entry is built after the access device observes the legitimate DHCP assignment process, especially the DHCP ACK that confirms the client’s assigned address. The resulting binding can then be used by protections such as IP Source Guard or Dynamic ARP Inspection. Huawei explicitly distinguishes these two mechanisms and the stages at which they operate.

Question 360. A branch router must let many private users share a dynamically assigned public WAN address, publish one internal HTTPS server, restrict inbound traffic with detailed Layer 3/Layer 4 matching, and let the central DHCP server identify each client’s access port. Which design BEST satisfies the requirements?

1. Use Easy IP for outbound Internet access, NAT Server for the HTTPS service, an advanced ACL with traffic-filter for detailed filtering, and DHCP Option 82 for client-location information
2. Use STP, OSPF, and LLDP only
3. Use one basic ACL for all requirements
4. Disable NAT and place every client directly on the Internet

Correct Answer: 1. Use Easy IP for outbound Internet access, NAT Server for the HTTPS service, an advanced ACL with traffic-filter for detailed filtering, and DHCP Option 82 for client-location information

Explanation:

Each requirement maps to a different edge-service function. Easy IP lets many internal users share the public IPv4 address of a WAN interface and works even when that address is dynamically obtained. NAT Server publishes the private HTTPS server through a fixed public address/port mapping. An advanced ACL can match source and destination addresses, protocol, and transport ports, while traffic-filter applies the desired interface filtering. Finally, DHCP Option 82 adds access-location information such as circuit and device identifiers so the central DHCP server can apply location-aware address or security policy.