Free Practice Questions for Huawei H12-711_V4.0 Exam

Explanation From HCIA-Security documents:

A SYN flood attack exploits the TCP three-way handshake mechanism by sending a large number of SYN packets without completing the handshake, causing the server or firewall to maintain excessive half-open connections and exhaust resources. Huawei firewalls provide multiple defense mechanisms at the TCP protocol level to mitigate this threat.

First, limiting the TCP connection establishment rate restricts how many new SYN requests are processed per second, preventing abnormal surges from consuming system resources. Second, limiting the number of half-open TCP connections ensures that the firewall does not allocate excessive memory and session table entries for incomplete handshakes, thereby protecting against resource exhaustion. Third, SYN cookie technology allows the firewall to avoid storing connection state information until the handshake is properly completed, effectively resisting SYN flood attacks without consuming large amounts of memory.

Interzone security policies primarily control traffic access based on zones and rules; they are not specifically designed as a SYN flood defense mechanism. Therefore, A, B, and C are correct.

Explanation From HCIA-Security documents:

In ESP transport mode, the authentication function provides data integrity and origin authentication for specific parts of the IP packet. The authentication calculation covers the ESP header, TCP/UDP header, user data, and ESP tail (including padding, Pad Length, and Next Header fields) . However, it does not include the outer IP header, because some IP header fields (such as TTL) may change during packet forwarding. It also does not include the ESP Authentication Data field itself, since that field stores the integrity check value result of the calculation.

In the diagram, range 3 correctly represents the portion starting from the ESP header up to the ESP tail, excluding the IP header and excluding the ESP Authentication Data field.

Range 1 only covers part of the payload, range 2 does not include the ESP header, and range 4 incorrectly includes the IP header. Therefore, option 3 accurately describes the authentication scope of ESP in transport mode.

Explanation From HCIA-Security documents:

A traditional packet filtering firewall mainly makes forwarding decisions based on information in the packet header, typically using fields such as source/destination IP address, protocol type, and for TCP/UDP traffic the source/destination port numbers in the transport-layer header. This works well for non-fragmented packets, because the IP header and the complete transport-layer header are present, and it can also work for initial fragments because the first fragment usually contains the transport-layer header (including ports) along with the IP header.

However, non-initial fragments (fragments after the first one) usually contain only the IP header and a continuation of the payload, but do not include the TCP/UDP header where port numbers and some key identifying fields exist. Because a packet filtering firewall relies on these transport-layer fields to match many rules, it cannot accurately apply port-based filtering to non-initial fragments. This limitation is why fragmentation can be abused to bypass basic filtering, and why more advanced firewalls/IPS features include fragment reassembly and deeper inspection. Therefore, non-initial fragments are the type that cannot be effectively filtered by a packet filtering firewall.

This statement is TRUE . A DMZ is a special security zone used to place servers that must provide services to external users while still being isolated from the internal trusted network. Typical examples include WWW servers, FTP servers, mail servers, and DNS servers . These systems need to be accessible from outside networks such as the Internet, but placing them directly inside the internal network would increase security risk.

The purpose of the DMZ is to create a buffer area between the Untrust zone and the Trust zone. External users can be allowed to access the public-facing servers in the DMZ according to security policies, while access from the DMZ to the internal network can be more strictly restricted. This design helps reduce the chance that an attacker who compromises a public server can directly reach sensitive internal systems.

On Huawei firewalls, the DMZ is one of the default security zones and is specifically intended for such semi-public service devices. Therefore, devices that provide external network services, such as WWW and FTP servers, can correctly be deployed in the DMZ .