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.
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.
