Re: 2 Colo's

Hello.

In real world implementation, the TTL issue (dead A record) is already present in the Internet (mostly in Asia, but also in Europe), I faced it during the migration of one site to another, a lot of users coming from a major local ISP were directed on the "old" IP address by their resolvers for days. I don't think it's acceptable for critical web sites and if it happens in the real world, the article is not just "something alarmist
based in theoretical situations".

Of course DNS-based GSLB solutions are not perfect, but there is not a single mention of the associated caveats (TTLs not honored, source-ip dns persistance broken, shuffled ordered lists...) in all products documentations I could read (except for the biaised DNS proximity based on the client's resolver, not the client itself). How can a user tune it's config correctly if he doesn't know the associated problems ?

regards,

Surya

--- En date de : Ven 29.5.09, Juan Canete <[email protected]> a écrit :

De: Juan Canete <[email protected]>
Objet: Re: [load balancing] 2 Colo's
À: "Load Balancing Mailing List" <[email protected]>
Date: Vendredi 29 Mai 2009, 0h35




 
 







Hi, 

   

My name is Juan Carlos Cañete (Radware-Alteon Technical Consultant
for EMEA) and I’m very happy to see how this article comes now and then
to the nowadays. In this forum I have seen the people “hate” this
article but for me it is perfect because it has helped me a lot of times to
show customers that the problem described at it can be overcome with ADC
solutions. 

   

I don’t know if you are using ADC solution in your actual
facility but I’m sure you are looking for fast service fail over,
optimization and high availability for your applications in case of failure or
disaster. DNS resolution is only the first tier for a GSLB and you must be able
to use other tiers, like the article describes, in order to guarantee a problem
with the DNS resolution. The final thought from the article can be summarize to
avoid using multiples sites because there is not a 100% perfect solution for
it. I can’t agree in this argument because if you have only one site you
can’t guarantee your applications to be available 24x7. In the same
article there are examples to kill the GSLB like DoS attack to one site, OK,
what will happen if you have only one site and you are under DoS attack? 

   

ADC solutions can help a lot under such situations because in
its responses can redirect the users to other sites that are not congested, I
mean, under attack and your clients will be available to get access to your
applications/services. The customer experience and the amount of GSLB developed,
not only by Radware, it is the best example that the article is just something alarmist
based in theoretical situations. 

   

My two cents, 

Juan Carlos  

   





De: [email protected]
[mailto:[email protected]] En nombre de Dane Ruyle

Enviado el: miércoles, 27 de mayo de 2009 21:01

Para: Load Baalancing

Asunto: [load balancing] 2 Colo's 





   

Hi all,

 

I'd like to hear your input on the best way to bring a second collocation
facility online.  We are a SAAS company.  Basically, our service is
all tied to a domain name; the www record.  

 

It was my intent to use 2 A records to the WWW lookup. Then, use GSLB to
control the traffic.    

 

This works fine when both sites are up and running, but what happens when one
goes down - rely on the built-in failover mechanism is DNS (the second A
record)?

 

There's a GSLB Page of Shame http://www.tenereillo.com/GSLBPageOfShame.htm

 

Would love to hear your input as I am going to be bringing a second one online.

 

Thanks for your time,

dane

  







Windows
Live™: Keep your life in sync. Check it out. 



 


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