This article is a reference for troubleshooting client-to-server communication by using common command line utilities. Command line utilities are useful because of their reporting capabilities. You can redirect the output of any of the commands shown here by appending an ">" (without the quotation marks) to the command line, followed by a path and file name.
Troubleshooting Basic TCP/IP Connectivity and NetBios Name Resolution
A line similar to the following should be displayed
Pinging DNS_name [192.168.###.###] with 32 bytes of data:
is the Domain Name System (DNS) name of the Exchange Server computer.
The Internet Protocol (IP) address that is listed must match the IP address of your Exchange Server computer. If the IP address is wrong, or if a line that reads "Unknown host ..." is displayed, name resolution is not working properly. In such a case, see the "Viewing the Contents of a Hosts File" section of this article and also click the article numbers below to view the articles in the Microsoft Knowledge Base:
How to Change Name Resolution Order on Windows 95 and Windows NT
XCLN: How to Ensure Proper Name Resolution
The next four lines that are displayed should be similar to the following:
Reply from 192.168.###.###: bytes=32 time<10ms TTL=62
These lines indicate that you have Transmission Control Protocol/Internet Protocol (TCP/IP) connectivity. If all four lines read "Request timed out," you have no TCP/IP connectivity.
Troubleshooting Intermittent TCP/IP Connectivity Issues
ping -t NetBios_name_of_Exchange_Server_computer
switch causes pinging to continue until stopped or interrupted. After you type this command you can interrupt the pings to check statistics by pressing CTRL-BREAK, and you can stop the process by pressing CTRL-C. A report similar to the following should be displayed:
Ping statistics for 192.168.###.###: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms
The Packets Lost
value is important because packets that are dropped is a sign of a poor physical connection.NOTE
: If you redirect the output of this command to a file, the size of that file will grow by approximately 29,000 bytes every 10 minutes.
Identifying Routers in a Path Between a Client and a Server
The output should look similar to the following:
Tracing route to <DNS_name_of_Exchange_Server_computer> [192.168.101.1] over a maximum of 30 hops: 1 <10 ms <10 ms <10 ms <DNS_name_of_first_router> [192.168.103.1] 2 <10 ms <10 ms <10 ms <DNS_name_of_second_router> [192.168.102.1] 3 <10 ms <10 ms <10 ms <DNS_name_of_Exchange_Server_computer> [192.168.101.1]
You can use this output to determine which routers or firewalls may be blocking the ports that are necessary for remote procedure call (RPC) communication.
If you do not want to know the DNS names of the hosts in the route to the target, you can add the -d
switch to the tracert NetBios_name/DNS_name/IP_address_of_Exchange_Server_computer
command. This switch tells the Tracert utility not to resolve the IP addresses that are encountered in the route to host names.
Viewing the TCP/IP Configuration of a Computer
On a computer that is running Microsoft Windows 95 or Microsoft Windows 98, click Start
, click Run
, and then type winipcfg.exe
. When an IP Configuration
dialog box is displayed, click More Info
. More detailed information is displayed.
The following command is for computers running Microsoft Windows NT:
A list of TCP/IP configuration parameters is displayed. The following is a sample of some of the information that is displayed:
Connection-specific DNS Suffix . : <DNS_domain_name>Description . . . . . . . . . . . : 3Com 3C918 Integrated Fast Ethernet Controller (3C905B-TX Compatible)Physical Address. . . . . . . . . : 00-C0-4F-xx-xx-xxDHCP Enabled. . . . . . . . . . . : YesAutoconfiguration Enabled . . . . : YesIP Address. . . . . . . . . . . . : 192.168.25.###Subnet Mask . . . . . . . . . . . : 255.255.255.0Default Gateway . . . . . . . . . : 192.168.25.1DHCP Server . . . . . . . . . . . : 192.168.25.50DNS Servers . . . . . . . . . . . : 192.168.30.100 192.168.30.101Primary WINS Server . . . . . . . : 192.168.25.60Secondary WINS Server . . . . . . : 192.168.25.61Lease Obtained. . . . . . . . . . : Monday, March 27, 2000 9:01:03 AM Lease Expires . . . . . . . . . . : Friday, March 31, 2000 9:01:03 AM
Determine if Dynamic Host Configuration Protocol (DHCP) is enabled. If it is enabled, make any necessary changes on the DHCP server instead of on the local computer; otherwise any modification to the TCP/IP parameters must be made to the local computer. Also make sure that the IP address and the default gateway (if one is specified) are on the same subnet. This is necessary to communicate with computers in other subnets. To determine whether the IP address and the default gateway are on the same subnet, apply the subnet mask to both the IP address and the default gateway. For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:
Understanding TCP/IP Addressing and Subnetting Basics
No Network Connectivity on TCP/IP-Based Network
Viewing the Contents of a Hosts File
For Windows NT:
For Windows 95 and Windows 98:
The contents of the Hosts file are displayed (by default) or output to a file (if redirection is used). During name resolution, the Hosts file is the first item that is checked, so any entries in this file are used for name resolution. Any lines that are preceded by a number sign (#) are ignored. The following is the proper format for a Windows Hosts file:
If your Exchange Server computer is listed, make sure that the IP address that precedes it is still valid. This is a static file, so if you make changes to your network or IP addressing scheme, you need to update this file. Also, both Windows NT and Windows 98 read this file dynamically, so if you make any changes to the Hosts file, you do not need to restart the computer for the changed mappings to take effect.