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The following table shows how Windows Embedded CE stores the resolved names and IPv4 addresses in the registry.

OS Names and addresses stored in

Windows CE 2.12 and earlier

HKEY_LOCAL_MACHINE\Comm\Tcpip\Hosts\ Host Name

Windows CE 3.0 and later


By default, Windows Embedded CE checks the cache. You can override the default and search for the name before checking the cache by setting the HKEY_LOCAL_MACHINE\Comm\Afd\ResolverCheckCacheFirstregistry key to 0. In this case, if Windows Embedded CE cannot obtain information by querying the named servers, it uses the cached value.

You can save name resolution failures to cache by setting the HKEY_LOCAL_MACHINE\Comm\AFD\ResolverCacheFailuresregistry key to 1.

The name resolution failure cache is only consulted when a cached entry exists for a successful search for the same name but of the other address type, A or AAAA. For example, the name resolution failure cache is consulted if a search is made for an IPv6 host (AAAA address) but an IPv4 host (A address) is found with the same name.

The getaddrinfofunction with the hints set to PF_UNSPEC performs parallel searches for both A and AAAA addresses.

The following table shows the behavior for subsequent name resolution attempts for the same name.

Host Search Address Type Behavior

Does not exist


Send query packets on the network

IPv4 only


Cached successful results returned

IPv4 only


Cached failure consulted because a successful cached entry exists for A results

See Also