Information Technology Reference
In-Depth Information
IP address for the network to which it's connected. This type of configuration can be used in the
following situations:
• A server is accessed by internal clients (clients on the network) and external clients (clients
on the Internet or an extranet). For example, you have a server for services such as file and
print sharing, DHCP, and DNS that also acts as a public Web server.
• A server provides resources for computers on multiple subnets of the network. Interfaces
can be configured for each subnet, which provides more throughput than is possible with
a single NIC.
• A server is configured as a router or VPN server. Both functions require multiple NICs.
For network connections to a LAN, Windows uses names such as Local Area Connection,
Local Area Connection 2, and so forth, which aren't very descriptive. Renaming each network
connection to describe the network it connects to is recommended. For example, if a server is
connected to internal and external networks, you might name one connection LAN-Internal and
the other LAN-External. If the server is connected to two internal networks, you could use the
network address in the names, such as LAN-172.31 and LAN-172.16. To rename a connection,
right-click it in the Network Connections window and click Rename.
When a server is multihomed, it's usually connected to two physical as well as logical net-
works. Each physical network likely has a router. Simply configuring a default gateway for each
interface might be tempting. However, Windows always chooses only one default gateway for
sending packets to remote networks. For example, a server could receive a packet through an
interface connected to the internal network and send the reply to the default gateway on the
external network. You probably don't want this to happen. To solve this problem, you can use
the Route command, explained in the next section.
Using the Route Command
Windows computers maintain a routing table that dictates
where a packet should be sent, based on the packet's destination address. The Route command-
line program enables you to display and alter the routing table's contents. Figure 8-8 shows par-
tial results of the Route Print command, which displays the contents of the routing table.
8
Figure 8-8
Results of the Route Print command
The results of the Route Print command are displayed in five columns. The first column,
Network Destination, is a network number against which an IP packet's destination address is
compared. The Netmask column displays the subnet mask associated with the network destina-
tion. The Gateway column is the address of the router where packets with a destination address
matching the network destination should be forwarded. The Interface column is the address of
the NIC the packet should be sent through to reach the gateway. The Metric column is the value
assigned to the route. If the routing table contains two or more entries that can reach the same
destination, the one with the lowest metric is chosen.
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