Traveling a Network

Traveling a Network using Ping and Tracert

Ping

In this post, I will review some things that the tools ping and tracert can assist in network troubleshooting. The outcomes of ping tell you a couple things right away.

1) DNS resolution. Before ping can even determine what, it is connecting to, it needs to know where it is going. When you run “ping google.com,” the very first line returns the IP of google.com based on your DNS server's query.

2) The replies measure the response time to get the reply from sending x bytes to the destination along with the packet size sent and TTL. Packet size can be adjusted for testing networks where jumbo frames are in use. 32 bytes is the default all networks support. The TTL tells you how many routers your packet went thru to get to the final endpoint. if a packet's TTL gets to 0, the router will drop the packet. TTLs function is to help keep the network clean from traffic getting caught in a loop.

3) Statistics. This tells you that based on sending x packets to y address, how many were sent, how many replies you received, and based on that, the percent lost.

4) The last section describes the times. It will provide you the time in milliseconds the minimum, maximum, and the average. Often the default of four pings is sufficient to see if a page, site, or computer is responding, aka up, but you can also run ping over a longer period using the –t option. the –t option runs the command indefinitely until ctrl+c is entered this way you can check the statistics over per se the next hour.







From my ping results, we can see that the time to reach Japan, is significantly longer than it takes to reach Australia. I would expect Google to load the fastest, followed by news.com.au, and finally yahoo.co.jp. There could be several reasons for the times including how busy it is or what other traffic is going across the same path.

Traceroute

Tracert – the Windows version tells us some equivalent items to ping, but instead of just pinging the end IP, it pings all of the hops on the way to the destination

1) DNS resolution. Like Ping, tracert depends on DNS to work and resolves each hop on the way to the destination. You are also notified that it will only attempt to trace the path over a maximum of 30 hops or routers on the way to the destination.

2) Number of Hops. Unlike ping, tracert sends three packets to every hop and shows you the times it took for each packet to return in ms. looking at the times shows if the connection is consistent or not. The final piece of information for each hop is the DNS resolution for the IP address.







According to the handout, if you see an asterisk instead of a time in ms, the packet timed out in route. One reason this could happen is due to a device set not respond to ping. Tracert also shows the path packets travel getting to their destination. If you know your network, or where your internet egress is, you can spot issues, despite it functioning.

The results of my tracert, yields some interesting data. It appears that the site for news.com.au is hosted in the US. from the result for yahoo.co.jp, we can see the path go thru Los Angeles, and then to Osaka Japan. The Australian site ends at 142.250.190.110 and is held by Google.

Dennis