Tag Info

Hot answers tagged

29

When I use the term "DNS Round Robin" I generally mean in in the sense of the "cheap load balancing technique" as OP describes it. But that's not the only way DNS can be used for global high availability. Most of the time, it's just hard for people with different (technology) backgrounds to communicate well. The best load balancing technique (if money is ...


18

At what point is it worth adding a CDN (content delivery network) to your website? When one of the following occurs: You're reaching a large, international audience. Careful analysis of your audience shows that many of them are 100 - 300ms Round Trip Time (RTT) away. You do the math, and discover that a large group of you customers are getting a ...


15

Your question is: "Is DNS Round Robin the ONLY way to assure instant fail-over?" The answer is: "DNS Round Robin is NEVER the right way to assure instant fail-over". (at least not on its own) The right way to achieve instant fail-over is to use BGP4 routing such that both sites use the same IP addresses. Using this the internet's core routing ...


12

Short answer: CDN's take your data and place it on many different servers around the world so that high traffic content can be delivered to the end user as quickly as possible. Long answer: CDN's distribute your file(s) to multiple edge locations and assign a URI to it. When a request is made the CDN evaluates the location of the request and routes it to ...


12

The app engine is a cloud computing platform and is not designed to be a CDN. While your data may be stored on multiple nodes those nodes are not edge-cache nodes so they will not offer the same benefits that a CDN would. You can compare GAE vs various CDNs using the CloudHarmony.com speed test. Here were the results when I tested today: Order Service ...


11

I was able to verify that it's working using rtmpdump found here: http://all-streaming-media.com/record-video-stream/rtmpdump-freeware-console-RTMP-downloading-application.htm Usage: rtmpdump -r "rtmp://example.fcod.llnwd.net/a1111/e11/test/example/file.flv" -o test.flv


10

CDN's are designed for scalability and performance, but not for high availability. At any given time, they may require access to the original files. Most people use them to store static files such as images, css and javascript files. Some can be configured to cache HTML, but that's only if you have a completely static website. If that were the case, you ...


10

In addition to what answered by @Gabriel-Talavera, I'd add a couple of notes: Network routing, as well as Geographical Load Balancing, is totally unrelated to "data synchronization" between different servers. They are two problems addressed with plenty of very different technologies. As the title of your question seems to be focused on the networking ...


9

It would depend on who is hosting your CDN. If you host your website on one server, and the CDN with a 3rd party then it is likely that your CDN will remain active when your website it down. This may not be the case however, as some CDNs only distribute content they can verify is on your website. A side note, CDNs are not for hosting your whole website. So ...


8

I can't really answer the "who should I use" part of the question (as it's off-topic), but given that I do have significant experience in making sites/applications scale for high-traffic loads, I can definitely suggest that you look at getting a Reverse-Proxy CDN. The last company I worked for used Yottaa for this, and were able to use their services to ...


8

The main metrics would be: Price. Performance. This further breaks down to small-file performance (where latency, i.e. time to first byte dominates) and large-file performance (where transfer rate dominates). Obviously, actually measuring this is darn hard, but here are some decent benchmarks to get you started. Geographical coverage for the regions you're ...


8

Sure -- it's called "Economic Denial of Sustainability". Not a huge amount you can do about it. Don't expect any CDN provider that bills by the byte to aggressively deploy any countermeasures, either, because it's in their interest to serve (and bill you for) as much traffic as possible.


8

You have to use the API to create a DistributionConfig that uses CustomOrigin (rather than S3Origin). Some documentation on how to do so here: http://docs.amazonwebservices.com/AmazonCloudFront/latest/APIReference/index.html?DistributionConfigDatatype.html#CustomOriginChildElements Then you have to create a Distribution using that DistributionConfig: ...


7

A CDN is used for any content that is going to be accessed a multitude of times in a lot of various locations. YouTube for example, uses a CDN. The main advantage of a CDN is that you have a local Point of Presence for the majority of your internet users. If you notice that you're getting a lot of traffic from North America and England and Brazil, there's ...


6

Now-a-days you can setup Custom Origin via the AWS Web console.


6

I would strongly recommend the use of a proxy such as varnish or squid rather than downloading the files and keeping them yourself, so that the proxy takes care of all of the cache expiry and other entertainments that make caching so much fun. If you're trying to cache content that is dynamically generated and doesn't have proper expiry information in the ...


6

So, is it true that, with multiple data centers and HTTP traffic, the use of DNS RR is the ONLY way to assure high availability? Clearly it is a false claim - you have only to look at Google, Akamai, Yahoo, to see that they're not using round-robin[*] responses as their sole solution (some may use it in part, along with other approaches.) There are ...


6

Because CDN'ing www is a Good Thing (TM). We do this at www.huffingtonpost.com, its good for offloading ~90% of all http requests to our site (not an estimate, comes from the graphs). If developers just use a small handful of basic tricks such as ajax loading dynamic stuff for individuals and appending timestamps or svn checkout numbers to urls as a "just ...


6

It is possible. However, one purpose of a CDN is scalability. You can expect the CDN to perform the same if you throw 100 visits at once or 1 million visits at once. As far as your setup goes, there's nothing that I can know with the information you provided, but I think that the point above is what makes a CDN so valuable. If you're creating a site that ...


6

CDNs are configured to not allow dynamic content to run. You are paying them for bandwidth not for processing power. The reason for this is for security of their servers as if you could run ASP.NET or PHP you'd have access to a lot more of their systems than you have now. Also there's session state issues, etc.


5

It obviously is slower. You Need 2 requests to see the IP address, not one. THAT SAID: If that is a differnce, you have a Problem - as the results are cached, we talk of a one time Overhead of WAY less than a second, given a proper DNS Service to start with. It is more - practically - a 0.05 second ONE TIME hit.


5

CloudFront requests come from the documented IP ranges as well as with a User-Agent string that includes Amazon CloudFront. You can block either, but with AWS's IP ranges expanding fairly frequently I'd go with the User-Agent block.


5

Unless I've entirely misread your question that's EXACTLY what a CDN does, actually very little other than that to be honest.


5

You cannot build a CDN with two servers. A real Content Delivery Network (CDN) has servers on several continents, and routes the end users to a server near him by means of TCP/IP Anycast, geo-aware DNS, HTTP redirects and HTTP proxying, or more likely combinations thereof. Your question is vague to the point of being un-answerable. If you just want to have ...


5

Move your static media off to another storage subsystem. That could either take the form of a large NAS, with NFS exports to your webserver or preferably, use an object store like Amazon S3 for your static media. With the right incantations, you can actually have your users' browsers upload files directly to S3. If that's not in the cards, though, you can ...


5

Very nice observation vmiazzo +1 for you !! I'm stuck exactly where you are .. baffled with how these CDN do their magic. Following are my guess on how CDN run their network : Use Anycast DNS (mentioned by Jesper Mortensen) to get the closest data centre They run a local network which span across different data centre which allow them to do something ...


4

No but you can fake it by using "/" in the name of the resource you are placing in the bucket. Many of the bucket browsers support this and show it as folders.


4

The trouble with CDNs is that they don't direct you based on your own IP address - they direct you based on the IP address of your DNS server... That could be completely wrong. And do read Paul Vixie's ACM article, it's bang on the money. Anyhow, if you've already got region.example.com set up and running, you could consider doing an HTTP redirect from ...


4

That is exactly what they call an origin pull CDN. These proxies will typically hold the content for a limited time duration and refresh it when requested. There are other kinds of CDN, those which allow you to upload the content directly to them as well.


4

They use their own DNS names, say www.example.com; but it's actually a CNAME record that points to www.example.com.akamaitech.net (or whatever).



Only top voted, non community-wiki answers of a minimum length are eligible