When data is sent over the Internet, it's sent in small blocks of
data, called
packets. Messages are divided into packets before they are sent,
and each packet is then transmitted individually and can even follow
different routes to its destination. Once all the packets forming a
message arrive at the destination, they are recompiled into the
original message.
Sometimes when you are trying to send or
receive data over the Internet you may experience timeouts, or a Web
server may be down, which prevents you from accessing services and
Web sites. There are two common programs that can be used to test
your Internet connection and even help you diagnose congestion
between your computer (your ISP) and the destination server you're
trying to reach. The programs you can use are called
Ping and
Traceroute.
Ping
Ping (also written as PING or ping) is a
utility that you use to determine whether or not a specific IP address is
accessible. Ping works by sending a packet to a specified
address and waiting for a reply. Ping is used primarily to
troubleshoot Internet connections and there are many freeware and
shareware Ping utilities available for download.
On a Windows PC you can run Ping using a command prompt.
To do this, go to the Windows Start button, choose Programs, then
MSDOS Prompt. When you get the C: prompt, type ping followed by
the destination server name or an IP address, for example,
ping
google.com. |
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Ping will test the speed of your connection to the
server and will tell you how long a packet (32 bytes in size) takes to go
from your computer to the host and back to your computer again.
Ping Localhost
When setting up a
network you can use the ping command to make sure all of the computers are
"alive" (at least in the TCP/IP sense). To do this, go to the Windows Start
button, choose Programs, then MSDOS Prompt. When you get the C: prompt, type
ping 127.0.0.1
If everything is OK, you should get the following
response (or something similar):
Pinging 127.0.0.1 with 32 bytes of
data
Reply
from 127.0.0.1: bytes=32 time<10ms TTL=32
Reply from 127.0.0.1: bytes=32 time<10ms TTL=32
Reply from 127.0.0.1: bytes=32 time<10ms TTL=32
Reply from 127.0.0.1: bytes=32 time<10ms TTL=32
This means that TCP/IP is working on
the machine that you are typing on. 127.0.0.1 is a special address that
"loops back" to the machine you are pinging from. You can also type ping
localhost and
receive a similar response, since
localhost and
127.0.0.1 mean the same thing.
RECOMMENDED READING:
Practically Networked Troubleshooting Guides
Traceroute
Traceroute is a utility that traces a packet from your computer to an
Internet host, but it will show you how many hops the packet requires to reach
the host and how long each hop takes. If you're visiting a Web site and
pages are appearing slowly, you can use traceroute to figure out where the
longest delays are occurring. Traceroute utilities
work by sending packets with low time-to-live (TTL) fields. The
TTL value
specifies how many hops the packet is allowed before it is returned. When a
packet can't reach its destination because the TTL value is too low, the
last host returns the packet and identifies itself. By sending a series of
packets and incrementing the TTL value with each successive packet, traceroute finds out who all the intermediary hosts are.
The original traceroute is a UNIX
utility, but nearly all platforms have something similar. Windows includes a
traceroute utility called tracert. On a Windows PC you can run traceroute
using a command prompt To do this, go to the Windows Start button, choose
Programs, then MSDOS Prompt. When you get the C: prompt, type tracert followed by the destination
server name or an IP address, for example: tracert
google.com
If any of the
hops come back with * Request timed out, this denotes network congestion and
a reason for slow loading Web pages and dropped connections.
You can basically use Ping and Traceroute to
self-diagnose problems with your Internet connection. When you view the
results this shows you where the problem lies &$151; with your own computer, on
the network, or to see if it is the server you are trying to reach that is
experiencing issues.
So, What's the
Difference Again?
The main difference between the common Ping and
Traceroute commands is that Ping is a quick and easy way to tell you if the
destination server is online and estimates how long it takes to send ands
receive data to the destination. Traceroute tells you the exact route you
take to reach the server from your computer (ISP) and how long each hop
takes.
|
DID YOU KNOW...
It is often believed that "Ping" is an abbreviation for
Packet Internet Groper, but Ping's author has stated that the
names comes from the sound that a sonar makes.
|
By Vangie Beal
Last updated: February 13, 2009
You can't map Ping or Tracert!
The
short story is you can't establish a mapping through a NAT firewall for
either the ping or tracert commands.
Go Beyond Ping and Traceroute With Cable Testing
Ethernet cabling is generally of high quality, network faults are more
likely to lie elsewhere. Software glitches, such as configuration
problems, and user shenanigans are the primary causes of network
problems (insert favorite horror story here).
Windows XP Network Troubleshooting
This
article shows how to troubleshoot TCP/IP connectivity between computers
on a Windows network.
The Penguin's Practical Network Troubleshooting Guide
There
is more to ping than you may realize, so let's take a closer look. |
