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This document provides information about service subdomains (formerly proxy subdomains). In cPanel & WHM version 11.42 and later, we modified Apache's configuration to properly use proxy subdomains with Secure Sockets Layer (SSL) protocol. In cPanel & WHM version 76, we renamed proxy subdomains to service subdomains. This name more clearly describes the subdomains’ purpose rather than a specific implementation.

Service subdomain explanation

Service subdomains provide access to cpsrvd over the standard http and https ports. They also provide configuration information for mail clients, as well as calendar and contacts clients. When you create a new account or create a new domain the system automatically creates service subdomains. You can find a list of these subdomains in the Subdomain ports section of this document below.


  • To use this feature, your system administrator must enable the Service subdomain creation setting in the Domains section of WHM's Tweak Settings interface (WHM >> Home >> Server Configuration >> Tweak Settings).
  • The system does not create service subdomains for newly created subdomains.

You can access the cPanel, WHM, and WebMail login interfaces via the associated service subdomain. Alternatively, you can log in via the associated port for a slight speed advantage. The following table compares the advantages of both login types:

Login TypeAdvantage

Service subdomain

For example:

  • Easier to remember than a port number.
  • Can access from a network with restrictive firewall (for example, the firewall restricts access to ports 80 and 443).


For example:

Slightly faster server response.

The configuration information service subdomains

The autodiscover and autoconfig service subdomains grant programs access to domain configuration settings. Programs access the cpcalendarsand cpcontacts service subdomains for calendar and contacts communication. The following tables lists service subdomains, with their associated program:

Service subdomainAssociated programs 
autodiscoverMicrosoft Outlook® 

For more information, read our Thunderbird and Outlook autodiscover and autoconfig support documentation.

cpcalendarsCalDav and calendar clients

For more information, read our How to Set Up Calendars and Contacts documentation.

cpcontactsCardDav and contacts clients

Subdomain ports

The following table lists the service subdomains with their associated port:


In cPanel & WHM version 62, we expanded Domain TLS to handle Server Name Indication (SNI) functionality for service subdomains. cPanel & WHM enables SNI functionality by default for SSL certificates on service subdomains. For more information about Domain TLS, read our What is Domain TLS documentation.

SubdomainSecure portNon-secure port



SSL only secures the whm service subdomain for resellers.










Additional documentation

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