Questions tagged [anycast]

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91 votes
8 answers
94k views

What is "anycast" and how is it helpful?

I'd never heard of anycast until a few seconds ago when I read "What are some cool or useful server/networking tricks?". The wikipedia "Anycast" article on it is quite formal and doesn't really evoke ...
username's user avatar
  • 4,785
80 votes
11 answers
26k views

Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?

Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique. The usual warning against DNS RR is that it is not ...
Valentino Miazzo's user avatar
122 votes
4 answers
230k views

What is the difference between unicast, anycast, broadcast and multicast traffic?

I have never had the privilege of working in an environment that required complicated routing or if it did require it, it was handled upstream of me. I've always used very simple static routing ...
user avatar
11 votes
3 answers
10k views

How do I get anycast for my servers?

I want to have anycast for my web service, but I cannot find any information on how to achieve this or any company that can help. I've found loads of companies offering anycast DNS, but that's not ...
Filip Haglund's user avatar
22 votes
3 answers
17k views

What is needed to use anycast IPs?

So, there're a bunch of questions on SF about the uses and how anycast IPs are cool. My approach is something more practical. What specifically I need to have to use one of those addresses? Do I need ...
coredump's user avatar
  • 12.8k
5 votes
3 answers
4k views

Practical Anycast

I've read How can I send visitors to the closest server using DNS? post, but there's still some thing, on a practical level that I don't understand. Say I have two servers. One in NY another in Paris....
Daniel's user avatar
  • 157
12 votes
3 answers
6k views

How does anycast work with tcp?

TCP, being stateful, should require subsequent packets to reach the same server. (Stateless) HTTP runs on top of TCP, and CDN's can use anycast. So how does TCP work with anycast? What if the syn ...
Filip Haglund's user avatar
1 vote
1 answer
276 views

Is it possible to determine how may servers is connected to an anycast address?

It's possible to set up several servers with the same IP-address, on the internet, using anycast address. Using routing protocols , the server geographical closest to you responds to queries. I ...
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