Traveling Through a Network

Network connectivity is established by identifying a destination server. Domain Name Resolution or IP Addresses are used to determine the destination. Our networks are configured to pass our requests up to the next stage in connection, which determines where/how to address the request. It passes from my PC to my work network, to the work network provider, then to various hub servers, and finally flows back to the destination provider and destination server. The geographical location can have several intermediaries between my provider and the provider of my destination, all of which can impact the speed of the request. The internet was designed for fault tolerance. There are multiple paths data can take to get from the destination back to your machine. The protocols used do not even guarantee the data comes back as one answer. Instead, it is chunked with headers that allow the receiving device to reorder the parts before presenting them to the user. 

Ping and traceroute are two great tools for network communications. As a developer, when I am integrating with new systems, I like to ping the system to make sure I have network connectivity to it. For ping, I get a yes/no of can I get to the desired system. Traceroute is more advantageous for when I cannot connect. I can trace the connectivity and see how far I get before the connection cannot continue. For example, systems inside our company may be working, but our upstream provider is down. Or I may be on a segregated network and unable to reach the destination network, requiring a firewall exception rule to be created to allow the systems to connect. Other options include my wireless or network connection not working correctly, in which case I would not be able to reach out past my own machine. Or there can be problems with DNS servers being down, and my system cannot translate the human-readable URL to a destination endpoint. The various responses we get from the ping and traceroute commands help us to establish which is the more likely case. 

Pinging google.com

Pinging sina.com.cn

pinging www.skyscanner.com.auLinks to an external site.


For the following traceroute commands, timeouts are occurring.

Tracert may time out due to several reasonsLinks to an external site.1Links to an external site.2Links to an external site.3Links to an external site.4Links to an external site.5Links to an external site.:

• The packets arrived at a router with a firewall that prevents traceroute online requests.
• The packets arrived at the subsequent router, but they were not able to return to the computer that sent them.
• The router has a connection problem.
• The device you are using does not have enough capacity to respond, or is configured to ignore (or not respond to) pings.
• The router may be configured to simply drop ICMP packets when higher priority traffic is ongoing.

Tracing to www.google.comLinks to an external site.

Tracing to sina.com.au

Tracing to skyscanner.com.au