1.5 Content Delivery Network Flashcards
What is a content delivery network (CDN)?
A globally distributed network of proxy servers, serving content from locations closer to the user.
What types of content are generally served from CDNs?
- HTML/CSS/JS
- Photos
- Videos
- Dynamic content (in some cases)
How does serving content from CDNs improve performance?
- Users receive content from data centers close to them
- Your servers do not have to serve requests that the CDN fulfills
What is a push CDN?
A CDN that receives new content whenever changes occur on your server, requiring you to upload content directly.
When is a push CDN most effective?
For sites with a small amount of traffic or content that isn’t often updated.
What is a pull CDN?
A CDN that grabs new content from your server when the first user requests it, caching it afterward.
What determines how long content is cached in a pull CDN?
A time-to-live (TTL) setting.
What are some disadvantages of using a CDN?
- Significant costs depending on traffic
- Content might be stale if updated before TTL expires
- Requires changing URLs for static content
What is the primary goal of CDNs?
To provide high availability and performance by distributing services spatially relative to end users.
What are some notable content delivery service providers?
- Akamai Technologies
- Edgio
- Cloudflare
- Amazon CloudFront
- Fastly
- Google Cloud CDN
What is the role of CDN nodes?
To reduce bandwidth costs, improve page load times, and increase global content availability.
How do CDNs optimize content delivery?
By directing requests to optimal nodes based on performance and cost.
True or False: CDNs can serve both static and dynamic content.
True.
What is server-load balancing?
A method to share traffic among multiple servers or web caches to improve scalability and reliability.
What does request routing in CDNs do?
Directs client requests to the content source best able to serve the request.
What is the Internet Content Adaptation Protocol (ICAP)?
A protocol developed to provide an open standard for connecting application servers.
What is a peer-to-peer (P2P) content delivery network?
A network where clients provide resources as well as use them.
What is a private CDN?
A CDN created by content owners to serve their own content, consisting of PoPs only for their use.
What advantages do telco CDNs have over traditional CDNs?
- Own the last mile
- Deliver content closer to the end-user
- Built-in cost advantage
- Better control over resource utilization
What is the Open Caching specification?
Defines a set of APIs allowing a Content Provider to deliver content using several CDNs consistently.
What is EDNS0 and how does it improve CDN performance?
An extension that allows CDNs to utilize the requesting client’s subnet IP address, reducing round-trip latencies.
What are virtual CDNs (vCDNs)?
CDNs that use virtualization technologies to reduce costs, increase elasticity, and decrease service delay.
What is the purpose of EDNS0 in DNS?
To optimize trip latencies and improve performance for clients using public DNS or non-local resolvers.
EDNS0 has drawbacks including decreased caching effectiveness, increased DNS resolution traffic, and privacy concerns.
What does vCDN stand for?
Virtual Content Delivery Network.
vCDNs use virtualization technologies to reduce costs, increase elasticity, and decrease service delay.
How does a vCDN improve service delivery?
By deploying virtual caches dynamically based on content type and server or end-user geographic location.
This approach helps to avoid traditional CDN limitations.
What are Image CDNs designed to do?
Serve multiple versions of the same image through HTTP based on browser properties.
The goal is to serve high-quality images while preserving download speed.
What are the three components generally supported by an Image CDN?
- A Content Delivery Network for fast serving of images
- Image manipulation and optimization
- Device Detection
Device Detection involves analyzing User-Agent strings, HTTP Accept headers, or Client-Hints.
What is the main difference between Pull CDNs and Push CDNs?
Pull CDNs cache content upon request, while Push CDNs require uploading all content beforehand.
Each has different benefits and costs associated with their usage.
What are the benefits of using a Pull CDN?
- Easier to configure
- Seamless storage and updating of content
- Lower maintenance required
Ideal for low traffic sites or those well-optimized with caching.
What is a potential drawback of a Pull CDN?
Lack of control over cache duration, leading to delays in updates being reflected.
Changes might take up to 24 hours to propagate.
What is a benefit of using a Push CDN?
Content is always available on CDN servers, reducing load times for large downloads.
More efficient for sites with videos or podcasts.
When might a Push CDN strain your server?
When pushing frequent updates or if the server is underpowered for high traffic.
It requires more server resources to sync data with the CDN.
What should you monitor after choosing a CDN type?
Usage over the first 1-3 months and loading times.
This helps determine which CDN type is best suited for your needs.
