Before dealing with network configurations and troubleshoot network problems, it is important to have an understanding of the basic Network Services available in Windows 7. Network services such as, DHCP, DNS, APIPA and NAT are important network features that enable your computer to communicate with others. IPv4 configuration and operation relies on these services, which include:
- DHCP (Dynamic Host Configuration Protocol) – Assigns IP addresses to hosts automatically. That is, the IP configuration of the LAN adapter is set automatically. Apart from the IP address and subnet mask, DHCP can also specify the default gateway and DNS servers’ settings. The DHCP handles for how long a computer can retain the given IP address (renewal and leasing), can have rules set for a specific set of addresses and can bind static IP addresses according to specific parameters such as, the MAC (Media Access Control) address of LAN adapters.
- DNS (Domain Name Services) – Resolve host names and fully qualified domain names (FQDN) to IP addresses. Conversely, the resolution of an IP address to a host or domain name is known as Reverse DNS. For example, quite often we use the command line utility ping to test the connectivity to a host. Rather than using the IP address we often use the host or domain name such as, www.windows7library.com to test because it is far easier to remember domain names. The ping utility resolves and shows the IP address of the domain name www.windows7library.com thanks to DNS services.
- NAT (Network Address Translation) – Translates internal private IP addresses to a public address used on the Internet. NAT makes it possible that many computers on a private network share one public IP address. A routing device between the Internet and the internal network is responsible for managing all translations and ensures that packets from the Internet reach the correct internal destination. The Public IP address space is governed by The Internet Assigned Numbers Authority (IANA) while Private IP addresses can be set by the individuals managing their own networks.
- APIPA (Automatic Private IP Addressing) – It is default configuration base of Windows platforms when no DHCP services are available. When the computer starts and is set as a DHCP client but finds no DHCP services on the network it defaults to APIPA. The default IP address that the computer gets in this scenario is in the range from 169.254.0.1 to 169.254.255.254 with a subnet mask of 255.255.0.0. APIPA does not configure a default gateway and hence, hosts on the APIPA configured network cannot communicate with other networks.
Note: In a small network, DNS, DHCP and NAT services can be provided by a computer running Windows 7 with ICS (Internet Connection Sharing) enabled.