Network Traversal

 Traveling Through a Network

Recently I did some testing on network statistics for three sites in varying locations. These were www.google.com (USA), www.sega.jp (Japan), and www.canada.ca (Canada). In my testing, the geographical location made little difference in results. 

The server in Canada had the fastest response time and the one in the USA had the slowest. Interestingly enough, the fastest server had the most hops to get to it. The one in Japan had the least amount of hops. 

However, all of the sites appeared to be using CDNs (content delivery networks) in order to function (an example of this can be seen below). This will have drastically improved routing and sped up delivery times as the function of a CDN is to cache data and redirect traffic to the closest server geographically. Had they not been using CDNs, I would fully expect the furthest server to have the longer response times, and potentially the highest number of hops in the network.

 

 

Troubleshooting

Ping is a very useful tool in troubleshooting for a variety of reasons. The first being that ping returns an IP address with it. 

Say you ping www.google.com and get "Ping could not find host www.google.com", you know that you likely are having a DNS issue. From there you could ping 4.4.4.4 to see if you get a response. If you do not, you don't have internet connectivity at all. If you do, you need to check your DNS server and settings. 

If you see lost packets instead, either the server is off or there is a break in the routing chain. This can be diagnosed by running a tracert in order to see where the packet loss is occurring and where the chain breaks. 

Both ping and tracert function by sending ICMP packets, so you can also get an error if ICMP packets are being blocked at the firewall level too either in network hardware or on servers (as seen below). 

 

 

Another useful tool for troubleshooting (on Windows to keep consistent with the command scheme) is nslookup. This tool allows you to run DNS queries on both FQDN (fully qualified domain names) as well as IP addresses. Say you want to know the FQDN for 172.217.2.46. You could run "nslookup 172.217.2.46" to get this result. This is useful for helping to diagnose DNS issues in networking which can cause a wide variety of issues with service resolution