Operating System course

YBET   Technical trainings

7. DOS, network commands (second part)

1. NET - 2. Hostname - 3. IPConfig - 4. Ping - 5. ARP - 6. Tracert - 7. Route - 8. Netstat


Network ipconfig command to view the IP properties of the computer. Under Win98, this command is equivalent to winipcfg on Windows. There's no equivalent Windows XP.

IPCONFIG displays a summary of the IP of the network card properties

For each card, we find the IP address (here, subnet mask (, and the default gateway (here

IPCONFIG/all displays a summary of the IP of the network card properties

Similar to the previous but fuller, IPCONFIG/all also displays the name of the host (from the computer), the description of Network card and its MAC address, if DHCP is configured and address server, DNS server, here the Skynet Internet service provider, the date of the lease and its expiration date.

IPCONFIG/renew to renew the IP address for all network cards

It is often easier (from Windows 2000) to disable and re-enable the network card via Windows via the toolbar state of Windows or by network connections.

IPCONFIG/release allows free IP address. The connection is more effective.

This command is rarely used

IPCONFIG/FLUSHDNS empty the cache of DNS resolution (from Windows 2000).

This particular command is used when changing in the c:\windows\system32\drivers\etc\hosts file. Then of a change in server for an internet site, it takes approximately 72 hours for all the Web DNS servers are aligned on the new hosting (and IP address). By inserting the line www.ybet.be for example, force your Web browser to login to the site directly to the IP To finish the command, you must flush the DNS cache via this DOS IPCONFIG/FLUSHDNS command. Caution remove the line once totally transferred.

IPCONFIG/registerdns refreshes DHCP leases and re-registers DNS leases

This command sometimes to correct some problems of network at startup of the machine connections.

IPCONFIG/displaydns Displays the contents of the dns resolver cache.

In the above example, we have manually point the IP address of the site ybet.be. The majority of the sites visited in time are included in this command. The option additional |more to view by pages as in the majority of the directories DOS commands.

IPCONFIF/showclassid (NIC) and /setclassid (NIC) displays and modifies the classID of the DHCP of the mentioned card class respectively. To display all cards, change the name of the NIC by *.

4. PING.

In it, the DOS command is useless without options. It allows to determine whether the connection to an IP address is effective in displaying orders actually received. It is based on the ICMP network protocol. This command returns no connection if the destination address is set with a firewall hardware not returning results to the query (respond to ping from Wan size) that we will see in the hardware 2 course. A massive use of this command is sometimes used to disrupt Internet servers.

PING X.X.X.X sends a ping command to the NIC whose IP address is X.X.X.X

PING www.site.com sends a ping a domain name. This option uses the DNS servers.

These are the 2 main uses. Some option have a few utilities.

PING destination -t sends a ping command to a destination (IP address or domain name) until it stops. CTRL + <PAUSE>momentarily stop scrolling, <CTRL>+<C>stop command

For example, this command can let know when a server reboots during a reboot remotely (via terminal server for example).

PING destination -n 10 sends the command to a destination (IP address or domain name) 10 X, this number is configurable.

Other options as f request not to fragment packets,-l size in decimal is used to send a packet of size set (always in decimal). This allows to determine the MTU (maximum transmission Unit) of an Internet connection for example.

PING f-l 1500 www.ybet.be sends a 1500-byte packet unfragmented to the site ybet.be

5. ARP

This command is used for the network ARP (address Reverse Protocol) Protocol. It allows to view and modify the IP addresses matches / physical (MAC network card). As this course is not a network course, I can only see the main option

ARP-a displays the match IP / MAC address of computers and connected devices. Dynamic connections use DHCP to configure the IP address.

6. Tracert

TRACERT X.X.X.X to display jumps when connecting to the IP X.X.X.X, IP addresses and host name address
TRACERT www.site.com to display jumps when connecting site.com, IP addresses and host name domain name.

.Different options do not display the hostname or limit the number of jump. As for the PING command, a server can not accept the command if it is configured for.


This command allows to change the routing tables. It is reserved for pure TCP/IP networks courses, I need contain only the main command:

ROUTE PRINT Displays the routing for the used computer tables.

8. Netstat

NetStat will display all active (tuned) ports on a computer both TCP and UDP. It allows for example to detect trojans and other malicious programs.
NetStat-a to display all ports on a computer both TCP and UDP, including those who are inactive.

Remember, for an INTERNET connection, only a few ports are open (both TCP and UDP) and certainly not the ports greater than 1024 (at rare ready exceptions). However, in an internal network, higher ports are often used, this does not play the internal security of the network.

NEXT > Summary of Network command

<- First network command on DOS

The hardware 1 course: computer and peripherals. The Hardware 2 course: networks, servers and communications