Tips to Speed Up your Site with Content Delivery Network Services.

1
Content Delivery Network

• Introduction
• Server Selection Policy
• Server Selection Mechanisms
• Conclusion

2
Content Delivery Network

• A Content Delivery Network or Content
  Distribution Network is a globally distributed
  network of proxy servers deployed in
  multiple data centers.
• The goal of a CDN is to serve content to
  end-users with high availability and high
  performance.
• CDNs serve a large fraction of the Internet
  content today, including web objects (text,
  graphics and scripts), downloadable objects
  (media files, software, documents), applications
  (e-commerce, portals), live streaming media,
  on-demand streaming media, and social networks.
• CDN Replicates the content
• On many server spread throughout the internet.
• Updating the Replicas
• Updates pushed to replicas when the content
  changes.

3
Server Selection Policy.

• Live server
• For availability
• Lowest load
• To balance load across the servers
• Closest
• Nearest geographically, or in round-trip time
• Best performance
• Throughput, latency,
• Cheapest bandwidth, electricity,

4
Server Selection Mechanism

• Routing Any cast Routing.
• Advantages No extra round trips.
• Route to nearby server.
• Disadvantages
• Different packets may go to different servers.
• Does not consider network or server load.
• Naming DNS-based server selection
• Advantages Avoid TCP set-up delay.
• DNS caching reduces overhead.
• Disadvantages Based on IP address of local DNS
  server.
• Hidden load effect.

1.2.3.4
DNS query
1.2.3.5
local DNS server
5
Conclusion

• The term CDN means many things to different
  people and is an umbrella term that covers a lot
  of different types of content delivery services.
  Video streaming, software downloads, web and
  mobile content acceleration, licensed/managed
  CDN, transparent caching, and services to measure
  CDN performance, load balancing, multi-CDN
  switching and analytics and cloud intelligence.
  Its a complex ecosystem with a lot of vendors
  both large and small and some CDN vendors cross
  over into other industries like security and WAN
  optimization.