IPv6 vs IPv4 – Causes for IPv6 Usage Over IPv4

ipv4ipv6windows

I have two servers both running Windows 2008 with IPV4 and IPV6 both running.

If on server1 I ping server2 like this

ping server2

The response I get is 

Pinging server2 [2002:9b08:a21::9b08:a21]

However if I ping server2 from my local machine (Windows 7 with both IPV4 and IPV6 running) I get

Pinging server2 [155.8.10.33]

The TCP/IP properties for IPV6 are identical on the server and on my local machine. However there are some differences in the properties from IPV4.

LocalMachine IPV4 Properties :
Adapter Propetiers For IPV6 On Local Machine

Server IPV4 Properties :

enter image description here

The only other difference I can see is that in ipconfig on the server "connection-specific DNS suffix" is blank where as on the local machine its set to the domain.

Best Answer

Windows implements RFC 3484 and uses a prefix table to determine which address to use when multiple addresses are available for a name.

By default, it favors IPv6 global unicast addresses over IPv4 addresses.

You can view/change the prefix policy through netsh:

// Open an elevated command prompt
// Enter the IPv6 context
> netsh int ipv6

// Then use one of the following commands
show prefixpolicies
set prefixpolicy
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