Monday, August 31, 2015

Ping

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Ping
Multiple Responses:
1.
Ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network and to measure the round-trip time for messages sent from the originating host to a destination computer and back. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects underwater; however, the acronym "PING" meaning "Packet InterNet Groper" has been in use since early days in computing for testing and measuring networks and the Internet.

Ping operates by sending Internet Control Message Protocol (ICMP) echo request packets to the target host and waiting for an ICMP echo reply. It measures the round-trip time from transmission to reception, reporting errors and packet loss. The results of the test usually include a statistical summary of the response packets received, including the minimum, maximum, the mean round-trip times, and usually standard deviation of the mean.

The command-line options for the ping utility and its output vary depending on implementation. Options may include the size of the payload, count of tests, and limits for the number of hops (TTL) that probes traverse. Many systems provide a companion utility ping6, for similar testing on Internet Protocol version 6 (IPv6) networks.

2.
Ping is the name of a standard software utility (tool) used to test network connections. It can be used to determine if a remote device (such as Web or gameserver) can be reached across the network and, if so, the connection's latency. Ping tools are part of Windows, Mac OS X and Linux as well as some routers and game consoles.

(Note: The term "ping" is also used colloquially by computer enthusiasts when initiating contact with another person via email, instant message or other online tools.)

Ping Tools
Most ping utilities (sometimes called ping tools) use Internet Control Message Protocol (ICMP). They send request messages to a target network address at periodic intervals and measure the time it takes for a response message to arrive. These tools typically support options like:
  • how many times to send requests
  • how large of a request message to send
  • how long to wait for each reply

The output of ping varies depending on the tool. Standard results includes:
  • IP address of the responding computer
  • length of time (in milliseconds) between sending the request and receiving the response
  • an indication of how many network hopsbetween the requesting and responding computers
  • error messages if the target computer did not respond

The Ping of Death
In late 1996 and early 1997, a flaw in the implementation of networking in some operating systems became well-known and popularized by hackers as a way to crash computers remotely over the Internet. The Ping of Death attack was relatively easy to carry out and very dangerous due to its high probability of success.

Technically speaking, the Ping of Death attack involved sending IP packets of a size greater than 65,535 bytes to the target computer. IP packets of this size are illegal, but applications can be built that are capable of creating them. Carefully programmed operating systems could detect and safely handle illegal IP packets, but some failed to do this. ICMP ping utilities often included large-packet capability and became the namesake of the problem, although UDPand other IP-based protocols also could transport Ping of Death.

Operating system vendors quickly devised patches to avoid the Ping of Death, and it is no longer a threat on today's computer networks. Still, many Web sites have kept the convention of blocking ICMP ping messages at their firewalls to avoid similar denial of service attacks.

3.
Ping is a basic Internet program that allows a user to verify that a particular IP address exists and can accept requests.

Ping is used diagnostically to ensure that a host computer the user is trying to reach is actually operating. Ping works by sending an Internet Control Message Protocol (ICMP) Echo Request to a specified interface on the network and waiting for a reply. Ping can be used for troubleshooting to test connectivity and determine response time.

As a verb, ping means "to get the attention of" or "to check for the presence of" another party online. The computer acronym (for Packet Internet or Inter-Network Groper) was contrived to match the submariners' term for the sound of a returned sonar pulse.
Tip: To find out the dot address (such as 205.245.172.72) for a given domain name, Windows users can go to their command prompt screen (start/run/cmd) and enter ping xxxxx.yyy (where xxxxx is the second-level domain name like "whatis" and yyy is the top-level domain name like "com").

4.
Ping is a networking utility program or a tool to test if a particular host is reachable. It is a diagnostic that checks if your computer is connected to a server. Ping, a term taken from the echo location of a submarine, sends data packet to a server and if it receives a data packet back, then you have a connection. The term "ping" can refer to the time it takes for a data packet to travel round-trip. It means "get the attention of" or "check the presence of". In a computer network, a ping test is a way of sending messages from a computer to another. Aside from checking if the computer is connected to a network, ping also gives indicators of the reliability and general speed of the connection.

Ping Test
A ping test is a method of checking if the computer is connected to a network. It also determines the latency or delay between two computers. It is used to ensure that a host computer which your computer tries to access is operating. A ping test is run for troubleshooting to know connectivity as well as response time.

Ping Execution
Microsoft (MS) Windows has a ping utility with it to run a ping test. It also has other utilities available for free web downloads. To do a ping test, just identify the website, remote server or computer by its IP address or name. It gives you an output confirming which connection is successful as well as the number series in milliseconds, the communication delay.

Like MS Windows, Linux and Mac OSX also provide a ping command program to run from the shell of the operating system (OS). Here is how a ping test is done in MS Windows.
1. Ping by IP address:
  1. Open the shell prompt or MS DOS prompt from the Start Menu
  2. Type: ping     (ENTER)

2. Ping a Web Site:

For Linux, open a terminal or telnet window as the equivalent to MS Windows command prompt. For Mac OS X, click on Applications folder, Utilities then Network Utility.

Ping Options
When should you run a ping test? You use it when you have connection problems. You run ping in order to detect where the problem comes from. If the ping shows to be successful but you still cannot reach the target, then the problem is not with you.

Your options depend on the implementation. Here are a few:
  • -? Help. This is used to display ping usage and syntax.
  • -c Count.  This means to send count packets then stop. Another way to stop is type [ctrl]-C. This is best for those who check their connection nature behavior from time to time.
  • -f Flood. Send packets soonest. This is to test network performance.
  • -l Preload. This is to send preload packets then go to normal mode. This is good for finding out the number of paces the router can handle quickly.
  • -n to seek for numeric output. This is used to prevent from getting into contact with a name server.
  • -p Pattern. A number of hexadecimal digits is called a pattern. It is to pad a packet end. This is applied when data-dependent problem is suspected.
  • -R is option for IP's Record Route. This is to determine the route the packets shall take. The target host may give the information.
  • -r is to skip routing tables. This applies when you think there is a routing problem and ping cannot find its way to the target host. This is only for hosts which can be reached directly even without routers.
  • -s size of packet. Alter packet size and check large packets to have them fragmented.
  • -t ping until stopped ([ctrl]-C).
  • -v for verbose. This means show ICMP packets with detailed information.
  • -w Timeout. This is for satellite, cellular and other networks with high latency. This means ping has a longer timeout so it identifies latency problems.

Example of the options usage is:
ping -t www.yahoo.com

Ping Results Interpretation
The output or a result of running a ping test can look like this:
1. Reply from 192.168.0.8: bytes=32 time=
  • Microsoft Windows ping outputs four messages - confirmation line, size in bytes, time and Time to Live (TTL). The latter is a number from 1 to 128. It is the number of networks which the ping passed through on its way to the target. The value 128 means that the device is on the local computer without other networks in between.

2. Request timed out.
  • No connection whatsoever.

3. Ping: cannot resolve mysample.com: Unknown host
  • Misspelled host name.

Using ping to troubleshoot connection problems narrows down the causes of the problem in your computer from the command prompt window. This diagnostic utility gives you an understanding how computer connection works by getting used to viewing the cornerstones of regular network.

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