+ @discussion Creates a dynamic store key that can be used to access
+ the per-interface network configuration information stored in
+ the dynamic store.
+ @param allocator The CFAllocator that should be used to allocate
+ memory for this key.
+ This parameter may be NULL in which case the current
+ default CFAllocator is used. If this reference is not
+ a valid CFAllocator, the behavior is undefined.
+ @param domain A string specifying the desired domain, such as the
+ requested configuration (kSCDynamicStoreDomainSetup) or the
+ actual state (kSCDynamicStoreDomainState).
+ @param ifname A string containing the interface name or a regular
+ expression pattern.
+ @param entity A string containing the specific global entity, such
+ as IPv4 (kSCEntNetIPv4) or DNS (kSCEntNetDNS).
+ @result Returns a string containing the formatted key.
+