From Azure documentation[1], some words are preserved and could not be used as a resource name.

Tested to set metadata.name in install-config with various preserved words mentioned in doc[1], following preserved words could not be set as metadata.name as a whole word or substring.

1) The following words can't be used as either a whole word or a substring in the name:
MICROSOFT
WINDOWS
2) The following word can't be used at the start of a resource name, but can be used later in the name:
LOGIN

Otherwise, installation failed with below error when creating user-assigned identity:

INFO Creating kubeconfig entry for capi cluster alogin-r6ksk 
INFO Waiting up to 15m0s (until 3:33AM UTC) for network infrastructure to become ready... 
INFO Network infrastructure is ready              
ERROR failed to fetch Cluster: failed to generate asset "Cluster": failed to create cluster: failed provisioning resources after infrastructure ready: failed to create public ip: PUT https://management.azure.com/subscriptions/53b8f551-f0fc-4bea-8cba-6d1fefd54c8a/resourceGroups/alogin-r6ksk-rg/providers/Microsoft.Network/publicIPAddresses/alogin-r6ksk-pip-v4 
ERROR -------------------------------------------------------------------------------- 
ERROR RESPONSE 400: 400 Bad Request                
ERROR ERROR CODE: DomainNameLabelReserved          
ERROR -------------------------------------------------------------------------------- 
ERROR {                                            
ERROR   "error": {                                 
ERROR     "code": "DomainNameLabelReserved",       
ERROR     "message": "The domain name label alogin-r6ksk is invalid. The name itself or part of the name is a reserved word such as a trademark. Please use a different name.", 
ERROR     "details": []                            
ERROR   }                                          
ERROR }                                            
ERROR -------------------------------------------------------------------------------- 
ERROR                                              
INFO Shutting down local Cluster API controllers... 
INFO Stopped controller: Cluster API              
INFO Stopped controller: azure infrastructure provider 

Or

ERROR failed to fetch Cluster: failed to generate asset "Cluster": failed to create cluster: failed provisioning resources after infrastructure ready: error creating user-assigned identity: please ensure your user credentials have the User Access Admin Role or if you are not utilizing an Azure Container Registry you can set installconfig.platform.azure.defaultMachinePlatform.identity.type: None to skip the creation of the identity: creation failed with: failed to create user assigned identity amicrosoft-shdd6-identity: PUT https://management.azure.com/subscriptions/53b8f551-f0fc-4bea-8cba-6d1fefd54c8a/resourceGroups/amicrosoft-shdd6-rg/providers/Microsoft.ManagedIdentity/userAssignedIdentities/amicrosoft-shdd6-identity 
ERROR -------------------------------------------------------------------------------- 
ERROR RESPONSE 400: 400 Bad Request                
ERROR ERROR CODE: ReservedResourceName             
ERROR -------------------------------------------------------------------------------- 
ERROR {                                            
ERROR   "error": {                                 
ERROR     "code": "ReservedResourceName",          
ERROR     "message": "The resource name 'amicrosoft-shdd6-identity' or a part of the name is a trademarked or reserved word." 
ERROR   }                                          
ERROR }                                            
ERROR -------------------------------------------------------------------------------- 


[1] https://learn.microsoft.com/en-us/azure/azure-resource-manager/troubleshooting/error-reserved-resource-name                      

    4.21 nightly build    

    Always

    1. Set metadata.name to Microsoft preserved words
    2. create cluster
    3.
    

    Installation failed during creating user-assigned identity.

    Installer should have pre-check and exit with proper message that such preserved words could not be used as metadata.name.

    Here is related bug on doc: https://issues.redhat.com/browse/OSDOCS-9182