Information Security Management (ISM) describes a set of controls that organizations employ to protect confidentiality, integrity, and availability. Confidentiality ensures that data is protected from unauthorized access or disclosure, integrity ensures that data is not modified without authorization, and availability ensures that data is accessible when it is needed. ISM is a crucial component of any organization's security strategy and is used to protect against threats such as data theft, data loss, and system outages. Reference: [1] https://searchsecurity.techtarget.com/definition/information-security-management [2] https://www.iso.org/standard/45170.html [3] https://www.bsigroup.com/en-GB/iso-27001-information-security/

NSX Gateway Firewall is a distributed firewall that provides security for east-west traffic within a virtual environment.
1. Firewall rules in Pre Rule category are applied to all gateways. This category contains system-defined rules that are always applied first to all gateways and cannot be modified. These rules include the default deny all rule and others that control basic connectivity.
2. Security Groups can be used in Applied-To column. Security groups allow you to group together VMs that have similar security requirements and then apply firewall policies to those groups. This way you can apply the same security rules to multiple VMs at once, instead of configuring the rules on each individual VM.
Reference:
VMware NSX-T Data Center documentation https://docs.vmware.com/en/VMware-NSX-T-Data-Center/index.html VMware NSX-T Data Center Gateway Firewall documentation https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.1/com.vmware.nsxt.firewall.doc/GUID-4C5D5A5F-8FDF-4F2A-9C5A-2C1903A3E5A5.html

The health status of an NSX Service Instance is an indicator of the overall health and functionality of the service.
For an NSX Service Instance to show as Up, the following two parameters must be functioning:
1. VMs must be available on the host - The VMs that are associated with the service must be present on the host and able to communicate with the NSX Manager. If a VM is not available on the host, the service will not be able to function properly.

When configuring members of a Security Group, the permitted membership criteria are Virtual Machine, Physical Machine, Cloud Native Service Instance, and IP Set.
For more information on configuring members of a Security Group, please refer to the NSX-T Data Center documentation: https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.0/nsx-t-3.0-security/GUID-C0F9A9A7-9A1E-41D9-A237-FED7A6F20A0A.html

For further reading, see the VMware NSX-T Data Center Administration Guide (https://pubs.vmware.com/NSX-T-Data-Center/index.html#com.vmware.nsxt.admin.doc/GUID-704E1B2F-1E43-4E7F-97F2-59BBF8F6C9F6.html) for more information on configuring firewall rules.