CDN distributes your content to geographically diverse servers (also knows as nodes) and then servers the content from closest node to the end users. In other words, users accesses a copy of the data near to the client, as opposed to all clients accessing the same central server, so as to avoid bottlenecks near that server. For example, www.cyberciti.biz servers the content from a central server located in USA (please note that the host command (DNS lookup utility) available under Apple OS X, Linux and UNIX like operating system. MS-Windows user should use the nslookup command):
$ host www.cyberciti.biz
www.cyberciti.biz has address 22.214.171.124 www.cyberciti.biz has IPv6 address 2607:f0d0:1002:51::4
On other hand files.cyberciti.biz servers the content using geographically diverse CDN based nodes. In other words contents from files.cyberciti.biz severed from closest node to the end users. This will result into increased speed and efficiency. For example, files.cyberciti.biz returns the following IP for all UK and European visitors:
$ host files.cyberciti.biz
files.cyberciti.biz is an alias for wac.3032.edgecastcdn.net. wac.3032.edgecastcdn.net is an alias for gs1.wac.edgecastcdn.net. gs1.wac.edgecastcdn.net has address 126.96.36.199
A query from North America returns different IP address, enter:
$ host files.cyberciti.biz
host files.cyberciti.biz files.cyberciti.biz is an alias for wac.3032.edgecastcdn.net. wac.3032.edgecastcdn.net is an alias for gs1.wac.edgecastcdn.net. gs1.wac.edgecastcdn.net has address 188.8.131.52
You can send ICMP ECHO_REQUEST to network using the ping command 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. The ping command displays whether the destination responded and how long it took to receive a reply. The following ping test was done from our USA based server:
$ ping -c 4 files.cyberciti.biz
PING gs1.wac.edgecastcdn.net (184.108.40.206) 56(84) bytes of data. 64 bytes from 220.127.116.11: icmp_seq=1 ttl=60 time=0.377 ms 64 bytes from 18.104.22.168: icmp_seq=2 ttl=60 time=0.398 ms 64 bytes from 22.214.171.124: icmp_seq=3 ttl=60 time=0.374 ms 64 bytes from 126.96.36.199: icmp_seq=4 ttl=60 time=0.560 ms --- gs1.wac.edgecastcdn.net ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3000ms rtt min/avg/max/mdev = 0.374/0.427/0.560/0.078 ms
The following ping test was done from UK based server:
$ ping -c4 files.cyberciti.biz
PING gs1.wac.edgecastcdn.net (188.8.131.52) 56(84) bytes of data. 64 bytes from 184.108.40.206: icmp_seq=1 ttl=60 time=2.88 ms 64 bytes from 220.127.116.11: icmp_seq=2 ttl=60 time=3.04 ms 64 bytes from 18.104.22.168: icmp_seq=3 ttl=60 time=3.42 ms 64 bytes from 22.214.171.124: icmp_seq=4 ttl=60 time=2.79 ms --- gs1.wac.edgecastcdn.net ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3000ms rtt min/avg/max/mdev = 2.795/3.036/3.420/0.239 ms
In short Content Delivery Network is:
- Global content delivery platform which is created created using smart software and network technology.
- It can speed up your website and scale up web applications.
- It can reduce buffering or jitters while watching HD video or audio content.
- It can increases speed and decreases latency for large file downloads.
- It can increases security for your web application.
- Users get content from whichever server (node) is close to them or has a good network connection speed.
- All CDN nodes are connected to high speed network links, which will result into faster download times and less vulnerability to network congestion.
- Faster and reliable page loads means better user experience.
This blog post is 1 of 4 in the "Networks & Applications of Distributed Computing Tutorial" series. Keep reading the rest of the series: