Permissions

If you need to assign different permissions to personnel in your enterprise to access your DNS resources, Identity and Access Management (IAM) is a good choice for fine-grained permissions management. IAM provides identity authentication, fine-grained permissions management, and access control. It helps you secure access to your cloud resources. If your Huawei Cloud account does not require IAM for permissions management, you can skip this section.

IAM is a free service. You only pay for the resources in your account.

With IAM, you can control access to specific Huawei Cloud resources. For example, if you want some software developers in your enterprise to use DNS resources but do not want them to delete DNS resources or perform any other high-risk operations, you can grant permission to use DNS resources but not permission to delete them.

IAM supports role/policy-based authorization and identity policy-based authorization.

The following table describes the differences between these two authorization models.

**Table 1** Differences between role/policy-based and identity policy-based authorization
Name	Authorization Using	Permissions	Authorization Method	Scenario
Role/Policy	User-permission-authorization scope	System-defined roles System-defined policies Custom policies	Assigning roles or policies to principals	To authorize a user, you need to add it to a user group first and then specify the scope of authorization. It is hard to provide fine-grained permissions control using authorization by user groups and a limited number of condition keys. This method is suitable for small- and medium-sized enterprises.
Identity policy	Policies	System-defined identity policies Custom policies	Assigning identity policies to principals Attaching identity policies to principals	You can authorize a user by attaching an identity policy to it. User-specific authorization and a variety of key conditions allow for more fine-grained permissions control. However, this model can be hard to set up. It requires a certain amount of expertise and is suitable for medium- and large-sized enterprises.

Assume that you want to grant IAM users the permissions needed to create ECSs in CN North-Beijing4 and OBS buckets in CN South-Guangzhou. With role/policy-based authorization, the administrator needs to create two custom policies and assign both to the IAM users. With identity policy-based authorization, the administrator only needs to create one custom policy and configure the condition key g:RequestedRegion for the policy, and then attach the policy to the principals or grant the principals the access permissions to the specified regions. Identity policy-based authorization is more flexible than role/policy-based authorization.

Policies and actions in the two authorization models are not interoperable. You are advised to use identity policy-based authorization. For details about system-defined permissions, see Role/Policy-based Authorization and Identity Policy-based Authorization.

For more information, see IAM Service Overview.

Role/Policy-based Authorization

DNS supports authorization with roles and policies. New IAM users do not have any permissions assigned by default. You need to first add them to one or more groups and attach policies or roles to these groups. The users then inherit permissions from the groups and can perform specified operations on cloud services based on the permissions they have been assigned.

DNS is a project-level service deployed for specific regions. When you set Scope to Region-specific projects and select the specified projects (for example, ap-southeast-2) in the specified regions (for example, AP-Bangkok), the users only have permissions for load balancers in the selected projects. If you set Scope to All resources, the users have permissions for DNS in all region-specific projects. When accessing DNS, the users need to switch to the authorized region.

Table 2 lists all system-defined permissions for DNS. System-defined policies in role/policy-based authorization are not interoperable with those in identity policy-based authorization.

**Table 2** System-defined permissions for DNS
Role/Policy Name	Description	Type	Dependencies
DNS FullAccess	Full permissions for DNS	System-defined policy	None
DNS ReadOnlyAccess	Read-only permissions for DNS. Users granted with these permissions can only view DNS resources.	System-defined policy	None
DNS Administrator	Full permissions for DNS	System-defined role	Tenant Guest and VPC Administrator, which must be attached in the same project as the DNS Administrator role

Table 3 lists common operations supported by system-defined permissions for DNS.

**Table 3** Common operations supported by system-defined permissions
Operation	DNS FullAccess	DNS ReadOnlyAccess	DNS Administrator
Creating a public zone	Supported	Not supported	Supported
Viewing a public zone	Supported	Supported	Supported
Modifying a public zone	Supported	Not supported	Supported
Deleting a public zone	Supported	Not supported	Supported
Deleting public zones	Supported	Not supported	Supported
Disabling or enabling a public zone	Supported	Not supported	Supported
Creating a private zone	Supported	Not supported	Supported
Viewing a private zone	Supported	Supported	Supported
Modifying a private zone	Supported	Not supported	Supported
Deleting a private zone	Supported	Not supported	Supported
Deleting private zones	Supported	Not supported	Supported
Associating a VPC with a private zone	Supported	Not supported	Supported
Disassociating a VPC from a private zone	Supported	Not supported	Supported
Adding a record set	Supported	Not supported	Supported
Viewing a record set	Supported	Supported	Supported
Modify a record set	Supported	Not supported	Supported
Deleting a record set	Supported	Not supported	Supported
Deleting record sets from multiple public zones	Supported	Not supported	Supported
Disabling or enabling a record set	Supported	Not supported	Supported
Exporting record sets	Supported	Not supported	Supported
Importing record sets	Supported	Not supported	Supported
Creating a PTR record	Supported	Not supported	Supported
Viewing a PTR record	Supported	Supported	Supported
Modifying a PTR record	Supported	Not supported	Supported
Deleting a PTR record	Supported	Not supported	Supported
Deleting PTR records	Supported	Not supported	Supported

Identity Policy-based Authorization

DNS supports identity policy-based authorization. Table 4 lists all the system-defined policies for DNS in identity policy-based authorization. System-defined policies in identity policy-based authorization are not interoperable with those in role/policy-based authorization.

**Table 4** System-defined policies for DNS
Policy Name	Description	Type
DNSFullAccessPolicy	Full permissions for DNS	System-defined identity policy
DNSReadOnlyAccessPolicy	Read-only permissions for DNS	System-defined identity policy

Table 5 lists common operations supported by system-defined identity policies for DNS.

**Table 5** Common operations supported by each system-defined identity policy of DNS
Operation	DNSFullAccessPolicy	DNSReadOnlyAccessPolicy
Creating a public zone	Supported	Not supported
Viewing a public zone	Supported	Supported
Modifying a public zone	Supported	Not supported
Deleting a public zone	Supported	Not supported
Deleting public zones	Supported	Not supported
Disabling or enabling a public zone	Supported	Not supported
Creating a private zone	Supported	Not supported
Viewing a private zone	Supported	Supported
Modifying a private zone	Supported	Not supported
Deleting a private zone	Supported	Not supported
Deleting private zones	Supported	Not supported
Associating a VPC with a private zone	Supported	Not supported
Disassociating a VPC from a private zone	Supported	Not supported
Adding a record set	Supported	Not supported
Viewing a record set	Supported	Supported
Modify a record set	Supported	Not supported
Deleting a record set	Supported	Not supported
Deleting record sets from multiple public zones	Supported	Not supported
Disabling or enabling a record set	Supported	Not supported
Exporting record sets	Supported	Not supported
Importing record sets	Supported	Not supported
Creating a PTR record	Supported	Not supported
Viewing a PTR record	Supported	Supported
Modifying a PTR record	Supported	Not supported
Deleting a PTR record	Supported	Not supported
Deleting PTR records	Supported	Not supported