Summary

The topics covered in this chapter prepare network administrators for verifying basic network connectivity. Administrators should be able to perform the following tasks:

1.	Use the ping command to verify connectivity between two networked nodes.
2.	Use the traceroute command to determine the path traversed by the packets flowing between two networked nodes.
3.	Use the whois command to determine the administrative information of a host or domain in a public network.
4.	Use the dig or nslookup command to determine the DNS and mail server details for a host or Internet domain.
5.	Use the netstat and nbtstat commands to determine TCP/IP sessions and statistics for network end stations.
6.	Use the arp command to verify Layer 2 information on TCP/IP hosts.

Table 2-9 provides a list of all the tools discussed in this chapter.

Table 2-9. Tools Discussed in This Chapter

Tool	Function	Supported OS	Installable Files
ping	Verifies connectivity and round-trip time	Windows, Linux, IOS, CatOS	Preloaded with all supported OSs
fping	Pings multiple hosts simultaneously; faster response	Linux	http://www.fping.com
hping	Adds functionality to ping	Linux	http://www.hping.org/
SmokePing	Provides prolonged and graphic version of Ping	Linux	http://people.ee.ethz.ch/~oetiker/webtools/smokeping/
traceroute	Traces the data path	Windows, Linux, IOS, CatOS	Preloaded with all supported OSs
whois	Determines administrative and registration information for an Internet domain	Linux	Preloaded with all supported OSs
nslookup	Queries DNS server to determine information about an Internet domain or host	Part of Windows and Linux	Preloaded with all supported OSs
dig	Queries DNS server to determine information about an Internet domain or host; advanced version of nslookup	Linux	Preloaded with all supported OSs
netstat	Determines TCP/IP active sessions and statistics	Windows, Linux	Preloaded with all supported OSs
nbtstat	Determines network information for remote Windows computers	Windows	Preloaded with all supported OSs