TCP/IP Configuration Settings in any network

The following table summarizes many of the configuration settings for a TCP/IP network.

Parameter	Purpose
IP address	Identifies both the logical host and logical network addresses.
Subnet mask	Identifies which portion of the IP address is the network address.
Default gateway	Identifies the router to which packets for remote networks are sent.
Host name	Identifies the logical name of the local system.
DNS server	Identifies the DNS server that is used to resolve host names to IP addresses.
WINS server	Identifies the WINS server that is used to resolve host names to IP addresses.
MAC address	Identifies the physical address. On an Ethernet network, this address is burned in to the network adapter hardware.

Keep in mind the following regarding TCP/IP configuration:

• All computers must be assigned a unique IP address.
• Hosts on the same physical network should have IP addresses in the same address range.
• The subnet mask value for all computers on the same physical network must be the same.
• Configure the default gateway value to enable internetwork communication.
• The default gateway address must be on the same subnet as the host's IP address.

Choosing the Addressing Method

The table below lists options for assigning IP addresses.

Method	Uses
Static (manual) assignment	Small number of hosts. Network will not change or grow. Hosts that must have the same address each time. For small networks (if the administrative time and cost is acceptable). For non-DHCP hosts (hosts that cannot accept an IP address from DHCP). To reduce DHCP-related traffic.
APIPA	Single-subnet network. No DNS services. Automatic configuration of IP address and subnet mask only. Small, non-subnetted networks. Implementation for which you do not need to customize the default address range.
DHCP	Small, medium, or large networks. Automatic configuration. Automatically deliver additional configuration parameters (such as default gateway, DNS servers).
Alternate	A single computer connects to two networks, one without a DHCP server. A computer is connected to a network using DHCP, but you want it to be properly configured when the DHCP server is unavailable.

You should know the following facts about IP address assignments:

• By default, all Windows computers try to use DHCP for TCP/IP configuration information.
• APIPA is used to automatically generate an IP address if the DHCP server is unavailable and if no alternate address is configured.
• The APIPA range is 169.254.0.1 to 169.254.255.255 with a mask of 255.255.0.0.
• If the computer assigned itself an IP address (using APIPA), this means the computer could not contact a DHCP server.
• When you configure a static IP address, you disable DHCP and APIPA.
• Use an alternate IP address to use DHCP on one network and static addressing on another without reconfiguring the connection.
• When you configure an alternate IP address, APIPA is no longer used when the DHCP server can't be contacted.
• You can rely on APIPA for your IP addressing solution, but only for a network with a single subnet. APIPA does not set the default gateway or name server address.

IP Addressing Facts

The following table lists the default IP addressing classes and masks:

Class	Address Range	Default Mask
A	1.0.0.0 to 126.255.255.255	255.0.0.0
B	128.0.0.0 to 191.255.255.255	255.255.0.0
C	192.0.0.0 to 223.255.255.255	255.255.255.0
D	224.0.0.0 to 239.255.255.255	(multicast addresses)
E	240.0.0.0 to 255.255.255.255	(experimental addresses)

You should also know the following address ranges that are reserved for private addresses. Use these addresses on a private network that is connected to the Internet through a network address translation (NAT) router.

• 10.0.0.0 to 10.255.255.255
• 172.16.0.0 to 172.31.255.255
• 192.168.0.0 to 192.168.255.255

Keep in mind the following facts about IP addresses:

• The first address in a range on the subnet is the subnet address. Typically, this address is not assigned to hosts.
• The last address in a range on the subnet is the broadcast address. Typically, this address is not assigned to hosts.

Troubleshooting TCP/IP

Use the following tips to troubleshoot TCP/IP:

• Use Ipconfig /all to verify your IP address, subnet mask, default gateway, and other IP configuration values.
• If the IP address is in the APIPA range (169.254.0.0 to 169.254.255.254), the computer could not contact a DHCP server. Use Ipconfig /renew to try contacting the DHCP server again.
• Use Ping (Packet Internet Groper) to send small packets to a computer to see if the computer responds. Microsoft recommends the following use of Ping:
1. Ping the loopback address (127.0.0.1). This verifies that the TCP/IP protocol stack has been properly installed.
2. Ping the local IP address assigned to the machine. This verifies communication to the NIC.
3. Ping the default gateway. This verifies connectivity to the default gateway or to another machine on the local network. This verifies that the local network is accessible.
4. Ping a remote host. This checks the connectivity between the default gateway and the remote host.
• Use Tracert to see the route packets take through an internetwork between two devices.
• Use Pathping to view the route of the connection and the connectivity response time. This can help identify where communication latency occurs.
• Use the Arp -d * command to remove all dynamic ARP entries from the ARP list. (Arp -d clears the ARP cache.)
• Use the Windows system logs to track DHCP service startup and shutdown as well as critical errors. 

Network Monitor and System Monitor in server 2003

Two common tools, Network Monitor and System Monitor, are useful in monitoring your system. While both can be used to gather some information related to network performance, Network Monitor is the tool you will use most often to analyze network traffic and gather information about communication between two computers. The following table compares the features of Network Monitor and System Monitor.

Characteristic	Network Monitor	System Monitor
Data collected	Captures packets (or packet fragments) and their contents. Reports statistics about network traffic.	Monitors system statistics, producing counters and charts of system performance. Monitors local system components including disk, processor, memory, and network statistics.
Data reports	View contents of sent and received packets. View network traffic statistics.	View graphs of system performance and counters.
Event tracking	Configure triggers to stop capture or execute a command based on a specific network traffic event (or packet type).	Configure alerts to log an entry, send a message, or run a program when a counter reaches a specific threshold.
Identifying captured data	Configure filters to capture only specific packets or to display only certain packets.	Select objects and counters to identify the statistics you want to track.

You should know the following facts about Network Monitor:

• The free version of Network Monitor that comes with Windows can only monitor traffic to and from the local computer.
• To capture all network packets, use the SMS version of Network Monitor.
• Even when using the SMS version, you cannot capture packets sent to other computers on other segments through a switch. (Switched traffic is only sent to the segment where the destination computer sits.)
• Use Dedicated Capture mode with Network Monitor to ensure you capture all packets.