DNS Round Robin

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basically you need to add the same record (e.g. www) with different IP addresses

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Steve

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ASKER

I don't have DNS installed on my computer, but I remember there is a checkbox for it and you enter your Webservers IPs in a list, and when the client request comes up the first IP on the top of the list is serviced to the client then that IP moves to the bottom of IPs list and the second on the list will be serviced to the next request and moves to the bottom of the list, and it keeps going on and on as long as clients keep requesting.

ASKER

Do you have a snapshot for this:

http://technet.microsoft.com/en-us/library/cc757191.aspx

I don't know what you're talking about where you enter the ip addresses, but here is the snapshot you requested:

Picture-1.png

ASKER

what about the snapshot for the IP addresses list, because it goes like a loop.
after the top IP in the list is given out it moves to the bottom then for previous second in the list will become the top and so on....

I know this provide load balancing when all the servers are on if one of them fail it doesn't.
But Round robin along with NLB I believe the load balancing and failover will be available.

I don't know about the snapshot that you are talking about. The IP addresses are in the A records (Like the first snapshot I posted).

ASKER

Let's say you have 3 web servers
so in DNS you will create 3 records CNAME records.
www 10.0.0.10 server1.mycompany.com
www 10.0.0.11 server2.mycompany.com
www 10.0.0.12 server3.mycompany.com

and you check the check box Enable Round Robin
at the registrar you resgister mycompany.com and you will get for instance IP 69.69.69.69
let's say first public client Client1 opens a browse and enter www.mycompany.com the registrar will route the request to 69.69.69.69 (our external IP in the firwall), the firwalll will have a NAT that translate 69.69.69.69 to our internal DNS for instance 10.0.0.1.
Now at our DNS level, how will Round Robin know just about the 3 records of the web servers and not about the rest of records that can be on the forward zone?

I'm confused as to what you're asking.

Are all of your webservers behind your firewall? If so, wouldn't you just enable round robin and then from there on make the same records?

e.g.

www 10.0.0.10
www 10.0.0.11
www 10.0.0.12

ASKER

in the DNS you have many records and you also put the following records
www 10.0.0.10
www 10.0.0.11
www 10.0.0.12

when you enable round robin, how does it know that it should go through only the 3 records you mentioned. The bottom line is I want to understand how round robin knows which records in DNS to take into consideration and which not.

when a dns server has multiple ips for the same FQDN, it rotates the ips while replying to different queries. this means it sends all ips in the reply but keep shifting which ip is at the top of the list of ips. clients usually pick the ip on the top of the list received as an answer. This server behavior in rotating ips is round robin

ASKER

so when you enable Round Robin, it will see by itself the records with the same FQDN and will rotate between them. No extra configuration just enable Round Robin?

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