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For cPanel & WHM version 11.50


Internet Protocol (IP) is the communications protocol that routes traffic across the Internet. IPv4, which stands for Internet Protocol version 4, carries the vast majority of Internet traffic. However, IPv4 only allows approximately four billion addresses, and there is currently a shortage of available IPv4 addresses. IPv6 addresses the problem of IPv4 address exhaustion.


If you use IPv6, the service network restart command removes the IPv6 addresses from the network device. To restart your IPv6 configuration, you must run the /etc/init.d/cpipv6 restart command after you restart the network service. For more information, read our The cpipv6 Script documentation.

IPv4 and IPv6 comparison

The following table lists some of the differences between IPv4 and IPv6:

FormatA 32-bit address that consists of four period-separated octets.A 128-bit address that consists of eight colon-separated groups of four hexadecimal digits. Hexadecimal digits use the numerals 0 through 9 and the letters A through F.
Address Example192.0.2.27



  • Often, IP addresses collapse (hide) 0's that start an octet. For example, the example IPv6 address may also resemble the following address: 2001:db8:85a3:42:1000:8a2e:370:7334.
  • IPv6 addresses with only 0's in the octet collapse completely, and several octets can collapse together. A double colon (::) symbolizes this. For example, 2001:0db8:85a3:0000:0000:0000:0370:7334 can become 2001:0db8:85a3::0370:7334. However, IPv6 addresses cannot contain more than one double colon.
Availability4.2 billion possible addresses.340 undecillion possible addresses. This is equivalent to 3.4 x 1038 addresses, or 2128 possible addresses.
AccessibilityAnyone can access an IPv4 address.You can only access an IPv6 address if you use an IPv6-enabled network and server.

Why should I want an IPv6 address?

  • While there is a finite number of IPv4 addresses, there is essentially no limit to the number of IPv6 addresses.
  • The shortage of IPv4 addresses causes some hosting providers' prices for dedicated IPv4 addresses to increase. 
    • The Internet authority that provides IP addresses to hosting providers (IANA) requires justification and audits of IP addresses to avoid waste. 
    • The availability of IPv6 addresses helps hosting companies and website owners avoid the impact of this shortage.

What can I expect when I acquire an IPv6 address?

  • Your server will use both an IPv6 address and an IPv4 address.
  • Most browsers try to access the IPv6 address first, but they implement a very short fail time. If the page does not load in that time, the browser accesses the IPv4 address for the site.
  • Eventually, more IPv6 options and functionality will become available.

Enable IPv6

You can enable IPv6 with WHM's Enable IPv6 interface (Home >> IP Functions >> Enable IPv6).

Services with IPv6 support

cPanel, Inc. plans to provide IPv6 support to all cPanel & WHM services. Our development team focuses on one service at a time in order to provide our customers with IPv6 support.
The following cPanel & WHM services currently support IPv6:
  • Apache
  • BIND
  • MyDNS
  • NSD
  • Dovecot
  • Courier

Additional information

For more information about IPv6, read the following third-party resources:

  • Wikipedia provides an in-depth explanation of IPv6. This article includes a brief history of IPv6, some comparisons between IPv4 and IPv6, and a technical explanation of IPv6 implementation.
  • Google provides a brief history and the logic behind IPv6.
  • You can test your current IPv4 and IPv6 status and availability.