Command-line utilities

Repair

As an alternative to ipconfig you can use Repair to renew LAN or high-speed Internet connection IP settings. Repair performs a series of commands that repair a connection. The commands that are invoked by Repair are listed below with their command-line equivalents

nbtstat

Nbtstat is a useful tool for troubleshooting NetBIOS name resolution problems. You can use the nbtstat command to remove or correct preloaded entries: nbtstat -n displays the names that were registered locally on the system by programs such as the server and redirector. nbtstat -c shows the NetBIOS name cache, which contains name-to-address mappings for other computers. nbtstat -R purges the name cache and reloads it from the Lmhosts file. nbtstat -RR releases NetBIOS names registered with a WINS server and then renews their registration. nbtstat -a name performs a NetBIOS adapter status command against the computer specified by name. The adapter status command returns the local NetBIOS name table for that computer plus the media access control address of the adapter. nbtstat -S lists the current NetBIOS sessions and their status, including statistics.

pathping

The pathping command is a route tracing tool that combines features of the ping and tracert commands with additional information that neither of those tools provides. The pathping command sends packets to each router on the way to a final destination over a period of time, and then computes results based on the packets returned from each hop. Since the command shows the degree of packet loss at any given router or link, it is easy to determine which routers or links might be causing network problems. A number of options are available, as shown in the following table. Option Name Function -n Hostnames Does not resolve addresses to host names. -h Maximum hops Maximum number of hops to search for target. -g Host-list Loose source route along host list. -p Period Number of milliseconds to wait between pings. -q Num_queries Number of queries per hop. -w Time-out Waits this many milliseconds for each reply. -i address Use the specified source address. -4 IPv4 Force pathping to use IPv4. -6 IPv6 Force pathping to use IPv6.

Ping

The ping command helps to verify IP-level connectivity. When troubleshooting, you can use ping to send an ICMP echo request to a target host name or IP address. Use ping whenever you need to verify that a host computer can connect to the TCP/IP network and network resources. You can also use ping to isolate network hardware problems and incompatible configurations.

Tracert

Tracert (Trace Route) is a route-tracing utility that is used to determine the path that an IP datagram takes to reach a destination. The tracert command uses the IP Time-to-Live (TTL) field and ICMP error messages to determine the route from one host to another through a network. tracert [-d] [-h maximum_hops] [-j host-list] [-w timeout] target_name

ipconfig

When you troubleshoot a TCP/IP networking problem, begin by checking the TCP/IP configuration on the computer that is experiencing the problem. You can use the ipconfig command to get host computer configuration information, including the IP address, subnet mask, and default gateway.

ipconfig /renew

When you use ipconfig /renew, all network adapters on the computer that uses DHCP (except those that are manually configured) try to contact a DHCP server and renew their existing configuration or obtain a new configuration.

ipconfig /all

When you use the ipconfig command with the /all option, a detailed configuration report is produced for all interfaces, including any configured serial ports

ipconfig / release

You can also use the ipconfig command with the /release option to immediately release the current DHCP configuration for a host.

netstat

You can use the netstat command to display protocol statistics and current TCP/IP connections. The netstat -a command displays all connections, and netstat -r displays the route table plus active connections. The netstat -o command displays process IDs so you can view the owner of the port for each connection. The netstat -e command displays Ethernet statistics, and netstat -s displays per-protocol statistics. If you use netstat -n, addresses and port numbers are not converted to names.