E2013 namespace, unbound and DNS round robin

Hi,
Just check Ross Smith's blog abuot
namespace for E2013. He stated on "Figure 1" that VIPs per DAGs are behind single namespace "mail.contsoso.com" and clients reach those by DNS round robin. Anybody knows the answers for the questions:
How clients find the other VIP1 if VIP2 is down, but client has got on the responce from the DNS with VIP2's IP?
Do you need to have one IP per DAG? Would be it be possible to have one VIP only?
Petri

Hi,
The re-connection is based on TTL value. You can look the following thread:
https://social.technet.microsoft.com/Forums/exchange/en-US/8381c957-1189-4380-9e05-48f10ec15933/support-dns-roundrobin-for-exchange-2013-clients?forum=exchangesvravailabilityandisasterrecovery
HLB can detect when a specific Client Access server has become unavailable and remove it from the set of servers that will handle inbound connections, but DNS round robin can't do this.
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Exchange 2013 and DNS Round Robin downside?

Hi guys,
I have a question regarding Exchange Server 2013 (SP1) and the use of DNS round robin.
I have a customer that currently is running 2 CAS servers with NLB and we are currently investigating if it would be appropriate to move to a DNS RR solution so we can remove the CAS servers and install the CAS role on the Mailbox servers.
(yes I know that CAS with NLB and Mbx with DAG cannot be used on the same server)
What would be the downside of DNS RR?
Request 1 will go to first MBX server, Reqeust 2 to second MBX server, Request 3 to third MBX server and then start over again. If MBX server 1 goes offline, it will still be used within the DNS RR solution and clients will be redirected towards that server.
But how will clients react? Will Outlook 2010/2013 timeout since the server is not responding and do a autodiscover lookup again and then hopefully jump on the DNS that points towards another server?
Is this true for pop/imap or a receive connector for SMTP relay aswell?

Hi Fredrik,
Hope this helps out...
Round robin doens't check the load on the network interfaces.It just passes on to the next one; for example Server1, Server2
If server1 has a lot of traffic on his nic he still get more traffic onto his nic when round robin wants to.
NLB gives some checkes on the load on the interfaces. Therefore it will make sure that that all servers has about the same amount of traffic.
In Windows NLB we can able to create port rules for the virtual ip which is not applicable when you go DNS Round Robin
DNS round robin the clients will see different IP addresses Wherea NLB uses single IP Address
DNS round robin is not a good solution for redundancy. If one of the nodes goes down, you first have to go and remove its A record from the DNS server but then it may take some time before such a change is propergated. In the meantime you may have a number
of clients attempt to access the dead IP.
With load balancing you can remove a host from the set immediately (if it doesn't detect an unresponsive host automatically). The only affect of a downed server on the clients would be if some of the clients had session
data on that server.
Exchange Queries

NLS Redundancy using DNS Round Robin

Hello, I have searched the internet and this forum for my question but I couldn't find the answer anywhere.
Would it be an option to use DNS Round Robin as a 'fail over' mechanism for the DA NLS Server?
To explain our situation a little: We have a few branch offices and it happens sometimes that the site-to-site VPN tunnel between the branch office and the main office breaks (e.g. internet outage in the main office). In those situations it would be best to
have a NLS server in another office to prevent users from losing conenctivity to the network because of the first NLS server being unreachable (we have a full-mesh network between the offices).
But how does the DA mechanism respond to a DNS result with multiple IP addresses when querying for the NLS server? Most browsers will go to the 2nd IP address in case the 1st IP address is unreachable in such a situation. Will DirectAccess also do this?
I hope I explained our situation and question OK.

Jason,
I may have found something else. Apparently netmask ordering uses a default subnet mask of /24 (255.255.255.0) This is why the subnet must match. Apparently you can change the netmask used by netmask ordering:
Description of the netmask ordering feature and the round robin feature in Windows Server 2003 DNS
http://support2.microsoft.com/kb/842197
Not every customer may use this solution, but it might provide an solution for some customers. It all depends on their address scheme. Allow me to explain...
Imagine you have one datacenter and three branch offices. Each branch office owns a /16 subnet:
- Datacenter (10.100.0.0/16)
- Branch Office 1 (10.110.0.0/16)
- Branch Office 2 (10.120.0.0/16)
- Branch Office 3 (10.130.0.0/16)
Of course the whole /16 sunnet is not used on a site, intead multiple VLAN's with a /24 subnet are used at each site. A VLAN for servers and clients.
Now imagine you have an NLS in each server VLAN at each site. You configure RR for those NLS. If you query from a server next to an NLS, that NLS will be on top of the DNS query result. if you query from a client in another VLAN, the client will get
random DNS results because the client has another network ID. This is because the default netmask used by netmask ordering is 255.255.255.0 (/24).
If you change the netmask used by netmask ordering to 255.255.0.0 (/16) that will give you the nearest NLS on top.
But not every customer uses a /16 subnet for each site. So, that's why it won't be usable for everybody.
Ok, it is not an Enterprise solution and does not get the nobel prize, but what do you think?
Boudewijn Plomp | BPMi Infrastructure & Security
This posting is provided "AS IS" with no warranties, and confers no rights. Please remember, if you see a post that helped you please click "Vote as Helpful", and if it answered your question, please click "Mark as Answer".
Ah, ok...sorry I assumed you knew that! Normally NMO needs to be 'tuned' to match the branch office subnets to get the expected/best results. That KB is pretty invaluable to setup it up properly. Like you say it does depend on customer having logical/consistent
subnet boundaries definitions for it to work effectively though. I never said NMO was perfect :)
Jason Jones | Security Consultant | Microsoft Consultant Services (MCS)

Exchange 2013 CAS DNS Round robin Public DNS Record

Dear All,
If I am going to use DNS round robin as CAS redundancy. How should I map the public DNS record? Do I need to map 2 public IP for 2 CAS server to the mail domain? THanks
Best Regards,
Elroy

Dear Elroy
I am not sure about the success rate of your implementations but yes if it is round robin what you require you need add 2 ip addresses.
Suggestion:
Why don't you implement a CAS with a load balancer and then you can map the Public IP to the one IP on the Load Balancer.
Good Luck.

How to configurate Weblogic using DNS round robin?

          Thanks to Cameron for your reply.
          So if I cluster servers using DNS round robin,
          how can I configurate?
          Could you show me step by step please?
          Because I've tried to config it so many times.
          Thanks again.


          Thanks to Cameron for your reply.
          So if I cluster servers using DNS round robin,
          how can I configurate?
          Could you show me step by step please?
          Because I've tried to config it so many times.
          Thanks again.

DNS Round Robin - Impact of one wrong entry

Hello All,
I need to configure an app such a way that its should reach AD servers (two Windows 2008 servers) using a common name (only one name can be appended) and also evenly distribute the load. I created two A record with same name (Round Robin) in Windows DNS
server which point to both AD servers IP addresses. I know better solution is Hardware Load Balancer, but it's not an option as of now.
I assume when one AD goes down Windows DNS still forwards the query to the failed server when the turn comes. What I would like to know is whether that query which goes to the failed server will be rerouted by the DNS server to the active server?
Regards,
AB

What I would like to know is whether that query which goes to the failed server will
be rerouted by the DNS server to the active server?
The answer is No. It should be your application that has the intelligence to try another DC if one is not reachable.
I would recommend that your application includes the intelligence to locate the closest available AD server. I started a Wiki about that here: http://social.technet.microsoft.com/wiki/contents/articles/24457.how-domain-controllers-are-located-in-windows.aspx
Microsoft DsGetDcName API can
be used: http://msdn.microsoft.com/en-us/library/ms675983(v=vs.85).aspx
This posting is provided AS IS with no warranties or guarantees , and confers no rights.
Ahmed MALEK
My Website Link
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My MVP Profile

UCCE + EM + DNS (ROUND ROBIN)

Hello guys,
We have a client using UCCE + CVP with Extension Mobility, we are going to point the CUCM EM (Publisher + Subscriber) to a DNS Server, the redundancy worked fine at our lab, althought take at least 1 to 2 minutes to Extension Mobility comes back, however, we have not tested it in an enviroment with UCCE. Is there any problem using DNS with contact center?
PS
We know that the DNS is not recomended by Cisco, ACE should be used as a SLB and HA to EM, but as this is a POC cenario, we are testing other solutions.
UCCE 8.5.(4)
CVP 8.5(1)
CUCM 8.5.1.14048-1

It's ok to use DNS with UCCE.
Sent from Cisco Technical Support iPhone App

RDS 2012 Connection Broker and round robin DNS?

Hi,
I have a set-up with three session host servers and one of them is also a connection broker. Round robin DNS is configured for the three servers and the clients, who are all on our internal networks, can connect just fine to the farm name. My
questions is, is there any point in having round robin configured since the connections still need to go through the CB? Could i just have one DNS-record for the farm name pointing to the CB? My initial though was that round robin would add
redundancy, but does it realy? I've tried to find answers on this but none of the articles and posts i've found are realy clear to me.
Quite often the initial connection for clients is slow and my theory is that it's caused by the RR DNS records.

Hi,
Thank you for posting in Windows Server Forum.
I think we need to have DNS RR entries for our RDS environment because DNS RR will be used by RDP clients to connect to the RD Connection Broker servers. Once when we allowed the entries of all server to DNS RR, when there is alternate connection need to capture
for following server it will provided by DNS RR.
During the connection process, the end nodes (RDVH, RDSH, RDWA) will get configured with all the RD Connection Broker server names, and they will randomly choose one to connect to. The RDP clients will use the DNS Round Robin name configured to connect to the
RD Connection Broker servers randomly.
More information.
RD Connection Broker High Availability in Windows Server 2012
http://blogs.msdn.com/b/rds/archive/2012/06/27/rd-connection-broker-high-availability-in-windows-server-2012.aspx
Hope it helps!
Thanks.
Dharmesh Solanki
TechNet Community Support

Exchange 2013 CAS - Round Robin DNS not working properly

I have exchange 2013 server (2MB, 2CAS) server. I created two dns records for mail.test.com, autodiscover.test.com pointing to my two CAS servers.
But the problem is if i switched of one cas server, client outlook not connecting automatically to other CAS server. By restarting the outlook also its not working. By restarting the system or running the command ipconfig /flushdns in command prompt, it
working.
is there any configuration iam missing, please advice how to achieve decent load balancing in Exchange 2013 CAS without going for third party Loadbalancer...

I have exchange 2013 server (2MB, 2CAS) server. I created two dns records for mail.test.com, autodiscover.test.com pointing to my two CAS servers.
But the problem is if i switched of one cas server, client outlook not connecting automatically to other CAS server. By restarting the outlook also its not working. By restarting the system or running the command ipconfig /flushdns in command prompt, it
working.
is there any configuration iam missing, please advice how to achieve decent load balancing in Exchange 2013 CAS without going for third party Loadbalancer...
If a CAS role server is down or unable to service clients, you have to remove it from DNS round-robin consideration manually. There is no health check with DNS round-robin unlike a true load balancer.
Also, I would set the TTL to a low value for the CAS servers in the round-robin.
Twitter!: Please Note: My Posts are provided “AS IS” without warranty of any kind, either expressed or implied.

RD Web Access / RD Connection Broker - NLB/Round Robin or both?

Hi
Can someone point me to documentation that can assist with Infrastructure scaling and HA config of the RD Web Access/RD CB roles?
We have a successful PoC consisting of RD Web and RD CB on a single server (no GW required as we're using UAG) and several hosts. Now looking to port to production, thinking of scalability and HA. Looking to serve 300-750 users.
Thinking so far:
RD Web Access role across 2 servers using NLB
RD Connection Broker across 2 servers - (maybe same as Web Access machines?) But CB appears to operate using DNS Round robin. (https://msfreaks.wordpress.com/2013/12/23/windows-2012-r2-remote-desktop-services-part-2/)?
Can CB use NLB?
Which is preferred for the CB role, NLB or DNS round robin?
Cheers
Lea

Thanks Amy, they're really useful links. Why is it so hard to find these....or even an implementation/scaling guide for 2012?
TP - you are my hero, thanks for answering so many of my posts :-)
I was hoping RD Connection Brokers supported NLB as I've also read this is a far superior technology (see below). Here's my architecture thinking:
1. Install the CB role on two individual servers
2. Add NLB to the CBs
3. Follow
here , here and thanks Amy
here for SQL and HA mode (we run Full SQL on an independent server)
Question(s):
a. If SQL is not using AlwaysOn and therefore an SPF, what are the consequences of SQL outage? Does RDS fail completely?
b. If SQL is an SPF, is it worth enabling HA for CB presumably to gain load balancing? This
is a fascinating graph that would suggest little need based on latency for our farm of 20 or so hosts! All servers are on VMware 5.5 therefore inherent redundancy.
We may still choose HA but possibly for MS patching reasons such the farm (minus SQL server) can be patched without downtime...
I found this NLB/RRDNS description useful also
Network Load Balancing is superior to other software solutions such as round robin DNS (RRDNS), which distributes
workload among multiple servers but does not provide a mechanism for server availability. If a server within the host fails, RRDNS, unlike Network Load Balancing, will continue to send it work until a network administrator detects the failure and removes the
server from the DNS address list. This results in service disruption for clients. Network Load Balancing also has advantages over other load balancing solutions—both hardware- and software-based—that introduce single points of failure or performance bottlenecks
by using a centralized dispatcher. Because Network Load Balancing has no proprietary hardware requirements, any industry-standard compatible computer can be used. This provides significant cost savings when compared to proprietary hardware load balancing solutions.
Thanks again
Lea

BO 3.1 Clustering and DNS

I have a question on how everyone is doing their clustering as related to DNS.
Our first server is up and running and to access it people use the server DNS name however when we go to a cluster, should I set up a generic name in DNS for the cluster and points to just the first server, or a DNS round robin for both?

Setup a generic name for the cluster and use round-robin for DNS.
Also update the CMS name in web.xml or web.config file under Infoviewapp war folder with CMS cluster name.
Thanks,
Hari

Confused by RDS Connection Broker and DNS

Hi,
I'm setting up the following in my lab to test before a production deployment:
RDSH01 - RD Session Host 1
RDSH02 - RD Session Host 2
RDSH03 - RD Session Host 3
RDSBG - RD Connection Broker
Everything seems to work great if I point my RDP client at one of the session hosts via a DNS round robin, it redirects me to whatever server has my disconnected sessions on and new sessions get put on servers with the least connections, great, however,
I have the following questions...
I've read on other threads that I should be pointing my RDP client at the Broker, not at a Round Robin DNS containing the Session hosts. That said, its working just connecting to the hosts and redirecting and load balancing accordingly. Is this
the right approach? (I've got RDS.domain.local pointing at RDSH01, RDSH02 and RDSH03)
I'm currently using a Self Signed Cert for RDS.domain.local which is great when initially connecting, however when I get redirected to another host it comes up with a warning for eg. RDSH02.domain.local as the Session Hosts have no certs on them.
From what I've read, you don't need to put certs on every Session Host as the connection goes via the broker but when I connect to the broker I get told I'm not authorised, I can only connect to the Session Hosts.
What am I missing here?
Many thanks,
Dave

Thanks, I'll do that when I get to the live environment. The client has 10 thin clients already at a remote location using a single RDSH directly, they're Windows 7 Embedded with the RDP update so I'll tweak them with the load balance details.
As for R2, unfortunately we put the order through too early for R2 and have no SA, I tried to blag an upgrade through our MS account manager but he couldn't help as the prices have gone up so we'd have to go back to distribution and re-order :(
The client is coming from a very old physical 2003 environment which hasn't been touched in years, the current 2012 RDS is 100x better than their full far desktop experience so we'll be fine. Its 80 users over 3 RDSH's with 32Gb RAM on each although
I may increase that as we have more in the pot. Basically 3 VMware hosts on the front of an Equallogic, each with 64Gb RAM.
I will need to have a look at HA RDCB but that just introduces a single point of failure on the SQL box, so would have to do that too, seems overkill, can I just remove the RDSH's from the collection and run without the broker if it dies and rebuild the
collection with a new broker?
How many SAN's will I need on my cert, I've got memories of having to make multiple requests the first time I did exchange years ago.
Think I'll write a step by step guide for this, I've looked at loads and most on the web don't cover the little details, just the main steps which are kinda obvious.

Round robin DNS for load balancing between multiple network adapters (Xserve)

I'm attempting to use 'round robin' DNS to load balance between the two ethernet adapters of an Xserve.
Both ethernet adapters are connected to the same LAN and have static IP addresses of 192.168.2.250 and 192.168.2.251.
The DNS zone for the server's local domain/host (macserver.private) has a machine record with both IP addresses (set up in the Lion Server UI).
Having read up on round robin DNS, I would have expected DNS requests for 'macserver.private' to be answered with the two IP addresses ordered at random, achiving my aim of requests being served at random via each ethernet adapter.
However this doesn't seem to be the case. Doing a 'nslookup' from any of the network clients results in the two IP addresses being listed in the same order everytime. And pinging 'macserver.private' only ever results in a response from the same address.
Does anyone know why this is the case? Does Lion Server use a non-standard DNS configuration? Are there any additional settings I need to configure in Lion's DNS server to make adopt a round robin approach to responding to requests?
Thanks in advance for any help!

Be careful what you wish for
Round Robin DNS is rarely the best option for 'load balancing'. At the very least it's subject to caching at various point on the network - even at the client side, once the client looks up the address it will cache that response - this means that subsequent lookups may be served from the client's cache and not refer back to the server. Therfore any given client will always see the same address until the cache expires.
I suspect this is what you're seeing.
You can minimize this by setting a lower TTL on the records. This should result in the response being cached for a shorter period, meaning the client will make more requests to the server, with a higher change of using the 'other' address.
However, you're also going to run into issues with the server having two interfaces/addresses in the same LAN. This isn't recommended.
As Jonathon mentioned, you may be better off just bonding the two interfaces. This will provide an automatic level of dynamic load balancing without the latency of DNS caches, as well as automatic failover should one link fail (as opposed to round robin DNS which will cause 50% of requests to fail until the client cache expires and a new lookup is performed (and, even then, there's still a chance the client will try to use the failed link).

Does anybody know any software for the Mac that I can run round robin, single and double elimination tournaments?

Does anybody know any software for the Mac that I can run round robin, single and double elimination tournaments? I help run tournaments but using excel for pool play and the web for bracket play, but if wifi is not available I have no way of running brackets for prize play. Can some one help point me in the direction of software that I can use locally on my Mac Pro.
Thanks,
Chris
<E-mail Edited by Host>

Splendid City Team Sports Scheduler, and Sports Scheduling Software System

EXS24 question on keyswitching and round robin

I imported a Giga patch into EXS24, and the Giga patch imported two groups which are keyswitches.
However, I don't want to keyswitch between them. I'd like EXS to alternate between the two groups. In Kontakt-speak, this is called round robin.
How can I get that to work? I scoured the plug-in reference manual and found nada.

It's not a well-detailed item, but EXS can do it. (It's also called "Round Robin" in Gigastudio.)
Let's say your zones have been assigned to two groups, "Clarinet Staccato 1" and "Clarinet Staccato 2," and you want them to alternate every time they're played to lessen the machine gun effect.
Load the instrument. Click "Edit" in the EXS plug-in window.
Enable the viewing of "Select by" for groups.
For Clarinet Staccato 1, set "Select by" to "Group:" Now assign the Group to "---start---"
For Clarinet Staccato 2, set "Select by" to "Group:" and assign group to "Clarinet Staccato 1."
In other words, one group "starts", and the other plays the next keystroke after the first group has been heard.

E2013 namespace, unbound and DNS round robin

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