Unicast IP Routing
Unicast IP Routing |
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To help simplify the configuration of small office/home office (SOHO) networks to the Internet, the NAT routing protocol for Windows 2000 also includes a DHCP allocator and a DNS proxy.
The DHCP allocator component provides IP address configuration information to the other computers on the SOHO network. The DHCP allocator is a simplified DHCP server that allocates an IP address, a subnet mask, a default gateway, the IP address of a DNS server, and the IP address of a DNS server. You must configure computers on the DHCP network as DHCP clients in order to receive the IP configuration automatically. The default TCP/IP configuration for Windows 2000, Windows NT, Windows 95, and Windows 98 computers is as a DHCP client.
Table 3.5 lists the DHCP options in the DHCPOffer and DHCPAck messages issued by the DHCP allocator during the DHCP lease configuration process. You cannot modify these options or configure additional DHCP options.
Table 3.5 DHCP Allocator DHCP Options
| Option Number | Option Value | Description |
|---|---|---|
| 1 | 255.255.0.0 | Subnet Mask |
| 3 | IP address of private interface | Router (default gateway) |
| 6 | IP address of private interface | DNS server (only issued if DNS proxy is enabled) |
| 58 (0x3A) | 5 minutes | Renewal time |
| 59 (0x3B) | 5 days | Rebinding time |
| 51 | 7 days | IP address lease time |
| 15 (0x0F) | primary domain name of NAT computer | DNS domain |
The DHCP allocator only supports a single scope of IP addresses as configured from the Address Assignment tab on the properties of the Network Address Translation (NAT) routing protocol in the Routing and Remote Access snap-in. The DHCP allocator does not support multiple scopes, superscopes, or multicast scopes. If you need this functionality, you should install a DHCP server and disable the DHCP allocator component of the NAT routing protocol.
The DNS proxy component acts as a DNS server to the computers on the SOHO network. DNS queries sent by a SOHO computer to the NAT computer are re-sent by the NAT computer as DNS queries from the NAT computer to the NAT computer's configured DNS server. Responses to DNS queries corresponding to outstanding requests of SOHO computers received by the NAT computer are re-sent by the NAT computer to the original SOHO computer.