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Name: Norah
Status: Student
Age: 20s
Location: N/A
Country: N/A
Date: Around 2001


Question:
What is "Ping and Traceroute commends" on the internet and how it works in details please?



Replies:
Norah,
PING Packet Internet Gopher

This is the simplest way to test or time the response of an Internet connection. PING sends a request to an Internet host and waits for a reply, or PONG. When you PING an address, you get a response telling you the number of seconds it took to make the connection. PING clients exist for a number of platforms, or you can use a UNIX or Windows 95 prompt to issue a PING command directly.

The TRACERT diagnostic utility determines the route taken to a destination by sending Internet Control Message Protocol (ICMP) echo packets with varying IP Time-To-Live (TTL) values to the destination. Each router along the path is required to decrement the TTL on a packet by at least 1 before forwarding it, so the TTL is effectively a hop count. When the TTL on a packet reaches 0, the router should send an ICMP Time Exceeded message back to the source computer.

TRACERT determines the route by sending the first echo packet with a TTL of 1 and incrementing the TTL by 1 on each subsequent transmission until the target responds or the maximum TTL is reached. The route is determined by examining the ICMP Time Exceeded messages sent back by intermediate routers. Note that some routers silently drop packets with expired TTLs and are invisible to TRACERT.

TRACERT prints out an ordered list of the routers in the path that returned the ICMP Time Exceeded message. If the -d switch is used (telling TRACERT not to perform a DNS lookup on each IP address), the IP address of the near- side interface of the routers is reported.

In the following example, the packet must travel through two routers (157.54.48.1 and 11.1.0.67) to get to host 11.1.0.1. In this example, the default gateway is 157.54.48.1 and the IP address of the router on the 11.1.0.0 network is at 11.1.0.67.

Thanks for using NEWTON.
Joe Noga


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