Explanation:

The cloud security shared responsibility model is a way of describing how the security tasks and obligations are divided between the cloud service provider (CSP) and the customer, depending on the type of cloud service model used. The cloud service models are:
* Software as a Service (SaaS): The CSP provides and manages the entire software stack, including the applications, data, runtime, middleware, operating system, virtualization, servers, storage, and networking. The customer only needs to access the software through a web browser or an application.
The customer is responsible for managing their own data and identities, as well as configuring the security settings of the software. The CSP is responsible for everything else, including patching the operating system and the applications12
* Platform as a Service (PaaS): The CSP provides and manages the platform layer, including the runtime, middleware, operating system, virtualization, servers, storage, and networking. The customer can deploy and run their own applications and data on the platform, using the tools and languages supported by the CSP. The customer is responsible for managing their own applications and data, as well as configuring the security settings of the platform. The CSP is responsible for patching the operating system and the middleware12
* Infrastructure as a Service (IaaS): The CSP provides and manages the infrastructure layer, including the virtualization, servers, storage, and networking. The customer can provision and use virtual machines, containers, or bare metal servers, and install their own operating system, middleware, applications, and data. The customer is responsible for managing and patching their own operating system, middleware, applications, and data, as well as configuring the security settings of the infrastructure. The CSP is responsible for the physical security and availability of the infrastructure12 References := 1: Shared responsibility in the cloud - Microsoft Azure 2: Cloud security shared responsibility model - NCSC

To understand DHCP snooping we need to learn about DHCP spoofing attack first.

DHCP spoofing is a type of attack in that the attacker listens for DHCP Requests from clients and answers them with fake DHCP Response before the authorized DHCP Response comes to the clients. The fake DHCP Response often gives its IP address as the client default gateway -> all the traffic sent from the client will go through the attacker computer, the attacker becomes a "man-in-the-middle".
The attacker can have some ways to make sure its fake DHCP Response arrives first. In fact, if the attacker is "closer" than the DHCP Server then he doesn't need to do anything. Or he can DoS the DHCP Server so that it can't send the DHCP Response.
DHCP snooping can prevent DHCP spoofing attacks. DHCP snooping is a Cisco Catalyst feature that determines which switch ports can respond to DHCP requests. Ports are identified as trusted and untrusted.

Only ports that connect to an authorized DHCP server are trusted, and allowed to send all types of DHCP messages. All other ports on the switch are untrusted and can send only DHCP requests. If a DHCP response is seen on an untrusted port, the port is shut down.

To add switches into the fabric for private cloud management, administrators can use the following two methods:
* PowerOn Auto Provisioning (POAP): This method allows the switches to be automatically discovered and provisioned by DCNM using a POAP configuration file. The switches are assigned an IP address and a startup configuration based on the fabric settings and policies. The switches are then added to the fabric and deployed with the VXLAN EVPN configuration. This method is suitable for greenfield deployments or adding new switches to an existing fabric12.
* Seed IP: This method allows the administrators to manually specify the IP address of the switches that they want to add to the fabric. The switches must have a reachable IP address and a username and password that match the fabric settings. The switches are then added to the fabric and deployed with the VXLAN EVPN configuration. This method is suitable for brownfield deployments or transitioning existing switches to DCNM management12. References: Cisco NDFC Fabric Controller Configuration Guide, Release 12.0.x, Cisco DCNM LAN Fabric Configuration Guide, Release 11.5(x).

Explanation/Reference: https://www.cisco.com/c/en/us/td/docs/security/firepower/60/configuration/guide/fpmc-config-guide- v60/Application_Layer_Preprocessors.html