 required for every network application though it might be possible to add unique features to solutions using these protocols. Applications based on DNS, ICMP (Internet control message), TELNET, and other utility protocols in the TCP/IP suite like ARP (address reso- lution protocol) or RIP (routing information protocol), can be effective tools for an operator performing network troubleshooting. Some of these methods are dis- cussed here (see also Figure 26.1). Domain name system: This is a client-server application that identifies each host on the Internet with the help of a unique user-friendly name referred to as a domain name. This functionality is useful as most people find it difficult to remem- ber strings of numbers like an IP address of a host. The DNS helps to convert domain names into the IP address. This is done by mapping an easily recogniz- able domain name with IP addresses. A worldwide network of DNS stores the list of domain names against IP addresses. Internet control message protocol: This is also referred to as PING. It is a proto- col that is used to report broken network connections or other router-level problems that end hosts might need to know. The PING utility available in most computers helps to identify if another computer in the network is switched on and how much delay there is over the connection to send messages to it. TELNET: This protocol is used for debugging servers and for investigating new TCP-based protocols. To debug a server, a TCP connection is made to the server C:\Windows\system32\cmd.exe F\Users\jithesh_sathyan> E\Users\jithesh_sathyan>ping 132.32.132.57 Pinging 132.32.132.57 with 32 bytes of data: Reply from 132.32 132.57 : bytes=32 time=16ms TTL=250 Reply from 32.32.132.57 : bytes=32 time=16ms TTL=250 Reply from 132.32.132.57 bytes=32 time=18ms TTL=250 Reply from 132.32.132.57 : bytes=32 time=30ms TTL=250 Ping statistics for 132.32.132.57: Packets: Sent = 4, Received = 4, Lost = 0 <0% loss>, Approximate round trip times in milli-seconds: Minimum = 16ms, Maximum = 30ms