Round Robin

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Anyone know where I can get a good HOWTO to set this up? Better yet,
can anyone tell me how to do it??!!! I looked in the MS Help and on
Google but could not find anything that explained it well.

Thanks
 
If a company has a web site called www.xyz.com, to handle demand, has
setup 3 web servers with identical content for the web site (WebServer1,
WebServer2 and WebServer3). There will be 3 DNS records for the IP
address of each server.

When a client sends a query to the DNS server to resolve www.xyz.com the
DNS server sends back the IP address of all 3 records with Webserver1 at
the top of the list, WebServer2 in the middle and WebServer3 at the
bottom.

If round robin is enabled on the DNS server, the next request for
www.xyz.com that the DNS server receives it will send all 3 records
again but this time will place WebServer3 at the top of the list,
Webserver1 in the middle and WebsServer2 at the bottom (rotating the
record at the top of the list for the last request to the bottom). This
provides a form of load balancing as the clients try to contact the
server at the top of the list first.

Round Robin can be enabled by using the DNS manager console. It is
configured at server level and can be set by checking the Round Robin
box on the Advanced tab of the Properties of your DNS server.

HTH
 
In
John Negus said:
If a company has a web site called www.xyz.com, to handle demand, has
setup 3 web servers with identical content for the web site
(WebServer1, WebServer2 and WebServer3). There will be 3 DNS records
for the IP address of each server.

When a client sends a query to the DNS server to resolve www.xyz.com
the DNS server sends back the IP address of all 3 records with
Webserver1 at the top of the list, WebServer2 in the middle and
WebServer3 at the bottom.

If round robin is enabled on the DNS server, the next request for
www.xyz.com that the DNS server receives it will send all 3 records
again but this time will place WebServer3 at the top of the list,
Webserver1 in the middle and WebsServer2 at the bottom (rotating the
record at the top of the list for the last request to the bottom). This
provides a form of load balancing as the clients try to contact
the server at the top of the list first.

Round Robin can be enabled by using the DNS manager console. It is
configured at server level and can be set by checking the Round Robin
box on the Advanced tab of the Properties of your DNS server.

HTH
Click to expand...

Round Robin is more of a pseudo load balance mechanism and not to be relied
upon. If one needs a true load balance mechanism, don't use DNS, but rather
use the NLB features built in to Windows 2000 and Windows 2003, or even
clustering in an Active/Active cluster, or better yet, products such as
Dell's BigIP. IBM and HP/Compaq have similar products.

Jonathan posted how Round Robin works. It's not necessarily by the "top of
the list" first.


--
Regards,
Ace

G O E A G L E S !!!
Please direct all replies ONLY to the Microsoft public newsgroups
so all can benefit.

This posting is provided "AS-IS" with no warranties or guarantees
and confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
Microsoft Windows MVP - Windows Server - Directory Services

Security Is Like An Onion, It Has Layers
HAM AND EGGS: A day's work for a chicken;
A lifetime commitment for a pig.
 
Hello Ace,

I completely agree with your statement "Round Robin is more of a pseudo
load balance mechanism". This is why, in my reply to the original
question, I stated "This provides a FORM of load balancing".

As for your statement, "Jonathan posted how Round Robin works", I do
not agree . If you read his link carefully, it focus's more on how
Round Robin will NOT work in certain environments than how it actually
does work in a Microsoft environment. As this is a Microsoft Public
News Group. I took it upon myself to explain how it works in a
Microsoft environment and in a later post provided a simple test to
prove this.

I would not recommend using this as a complete load balancing solution
though I have used this myself as a cheap alternative very successfully
(you need to be aware of the full environment to be sure it will work as
planned). A couple of examples: An internal read only web site with
multiple servers and a TS farm using a Session Directory Server.
 
In
John Negus said:
Hello Ace,

I completely agree with your statement "Round Robin is more of a
pseudo load balance mechanism". This is why, in my reply to the
original question, I stated "This provides a FORM of load balancing".

As for your statement, "Jonathan posted how Round Robin works", I do
not agree . If you read his link carefully, it focus's more on how
Round Robin will NOT work in certain environments than how it actually
does work in a Microsoft environment. As this is a Microsoft Public
News Group. I took it upon myself to explain how it works in a
Microsoft environment and in a later post provided a simple test to
prove this.

I would not recommend using this as a complete load balancing solution
though I have used this myself as a cheap alternative very
successfully (you need to be aware of the full environment to be sure
it will work as planned). A couple of examples: An internal read
only web site with multiple servers and a TS farm using a Session
Directory Server.
Click to expand...

....Or multiple Proxies serving the infrastructure. Jonathan has his own way
of defining things. I haven't seen your post yet, but here's a Microsoft
link I think you were referring to:

Configuring round robin:
http://www.microsoft.com/resources/...ard/proddocs/en-us/sag_DNS_imp_RoundRobin.asp

Network Load Balancing compared to other solutions:
http://www.microsoft.com/windows200...advanced/help/planning_limitations_of_NLB.htm

Prioritizing local subnets
http://www.microsoft.com/resources/...ocs/en-us/sag_dns_imp_localsubnetpriority.asp

And BIND:

Internet Software Consortium - BIND Documentation - about Round Robin and
load balancing:
http://isc.org./products/BIND/docs/bind-load-bal.html


Looking forward to your post.
:-)

Ace
 
I have the Round Robin and the Netmask Ordering enabled and want load
balancing Round Robin.
If I disable the Netmask Ordering and query the record "mydomain.br", is
returned the rotated list of DCs (A) address.
This DCs in different sites.

Exist problem in disabled the Netmask Ordering (traffic, replication...)?
 
In Mabson Lins <Mabson (e-mail address removed)> made a post then I
commented below
:: I have the Round Robin and the Netmask Ordering enabled and want load
:: balancing Round Robin.
:: If I disable the Netmask Ordering and query the record
:: "mydomain.br", is returned the rotated list of DCs (A) address.
:: This DCs in different sites.
::
:: Exist problem in disabled the Netmask Ordering (traffic,
:: replication...)?

Round Robin response with Netmask Ordering turned on, depends on the
querying client. If the querying client is not on a subnet that any of the A
records point to, it will go into rotation. If the client is on the same
subnet as one ot the records, it will be offered that record.

In your case, I'm not totally sure of the setup. Also, if you are worried
about what DC responds, that depends on the querying application. If the app
is AD aware and Site aware, it will respond with the DC in the same Site as
the client.

--
Regards,
Ace

G O E A G L E S !!!
Please direct all replies ONLY to the Microsoft public newsgroups
so all can benefit.

This posting is provided "AS-IS" with no warranties or guarantees
and confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
Microsoft Windows MVP - Windows Server - Directory Services

Security Is Like An Onion, It Has Layers
HAM AND EGGS: A day's work for a chicken;
A lifetime commitment for a pig.
 
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