application and services these queues in a round-robin fashion. IPv6 support IPv6 has to be installed and configured from the command line using the netsh interface ipv6 context as there is no GUI support. After the network interface's link-local address is assigned, stateless autoconfiguration for local and global addresses can be performed by Windows XP. Static IPv6 addresses can be assigned if there is no IPv6 router on the local link. Transition mechanisms such as manually configured tunnels and 6to4 can be set up. Privacy extensions are enabled and used by default. 6to4 is automatically activated for public IPv4 addresses without a global IPv6 address. Other types of tunnels can be set up include: 6over4, Teredo, ISATAP, PortProxy. Teredo also helps traverse cone and restricted NATs. Teredo host-specific relay is enabled when a global IPv6 address has been assigned, otherwise Teredo client functionality is enabled. The Windows XP DNS resolver can only make DNS queries using IPv4, it does not use IPv6 itself as a transport to make the query. However, when a DNS query sends back both IPv4 and IPv6 resource records, IPv6 addresses are preferred. Windows XP does not support DHCPv6 and PPPv6/IPv6CP. An open source DHCPv6 implementation called Dibbler is available, although stateless autoconfiguration largely makes it unnecessary. Background Intelligent Transfer Service Windows XP includes the Background Intelligent Transfer Service, a Windows service that facilitates prioritized, throttled, and asynchronous transfer of files between machines using idle network bandwidth. BITS will only transfer data whenever there is bandwidth which is not being used by other applications, for example, when applications use 80% of the available bandwidth, BITS will use only the remaining 20%. BITS constantly monitors network traffic for any increase or decrease in network traffic and throttles its own transfers to ensure that other foreground applications (such as a web browser) get the bandwidth they need. BITS also supports resuming transfers in case of disruptions. BITS version 1.0 supports only downloads. From version 1.5, BITS supports both downloads and uploads. Uploads require the IIS web server, with BITS server extension, on the receiving side. Windows XP components such as Windows Update use BITS to download updates so only idle bandwidth is used to download updates and downloading can be resumed in case network connectivity is interrupted. BITS uses a queue to manage file transfers and downloads files on behalf of requesting applications asynchronously, i.e., once an application