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

Similar Messages

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.

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.
Best regards,
If you have feedback for TechNet Subscriber Support, contact
[email protected]
Belinda Ma
TechNet Community Support

Introduction of New OAB Architecture in Exchange 2013 and Some General Troubleshooting methods

Exchange 2013 is different from previous versions of Exchange server on architecture, some of the old features have been changed. In this FAQ, I will demonstrate the changes on OAB and list a common issue for your reference.
[Agenda]
1. Differences between Exchange 2007/2010 OAB and Exchange 2013 OAB
a. Generation
b. Distribution
c. Download
2. Common issue and troubleshooting
3. More information
[Difference between Exchange 2007/2010 and Exchange 2013 on OAB]
As we know, OAB in Exchange 2007/2010 has 3 points, OAB files generated from MBX server, distributed to CAS server and downloaded to Outlook client. However in Exchange 2013, these 3 points have a little different from previous servers. For example, the OAB
Distribution process doesn’t depend on Microsoft Exchange File Distribution service anymore. Now let me show you the changes of OAB in Exchange 2013.
[OAB Generation]
====================
Exchange 2007/2010:
1. OAB generation server is the specific MBX server which has –server property.
2. If MBX01 is down, OAB generation will be affected.
3. Previous Server using Microsoft Exchange System Attendant service for OAB generation.
4. OAB generation is a scheduled process. By default, OAB files generated at 5:00AM every day.
5. The OAB files which generated from MBX server are located in following path:
C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\OAB\GUID folder
Exchange 2013:
1. OAB generation server is the MBX server that hosts a special type of arbitration mailbox, called organization mailbox. Thus, the same OAB files could be generated from multiple
MBX servers.
2. If one of the MBX server down, other MBX server still have the ability to generate the specific OAB files.
3. Exchange 2013 server using OABGeneratorAssistant for OAB Generation.
4. OAB generation is a throttled process. It depend on the Server workload.
5. The OAB files which generated from MBX server are located in following path:
C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\OAB\GUID folder
[OAB Distribution]
====================
Exchange 2007/2010:
Previous Servers use Microsoft Exchange File Distribution service to distribute OAB files from MBX server to CAS server. The distributed oab files stored in CAS server.
Exchange 2013:
The OAB files doesn’t distributed to CAS server. The OAB files only stored in MBX server.
[OAB Download]
====================
Exchange 2007/2010:
If Autodiscover works fine, Outlook should use OAB URL to get the OAB files and download it.
If Autodiscvoer doesn’t work, authenticated users can also get the OAB from the CAS server local disk.
Exchange 2013:
Microsoft Exchange File Distribution service has been removed from Exchange 2013 and the OAB files stored in MBX server. CAS server will proxy all OAB download requests to the appropriate MBX server.
Outlook also use Autodiscover to get the OAB URL and download it.
[Common issue and Troubleshooting]
Issue: Outlook doesn’t download OAB files automatically. When I try to manually download OAB, get this error: Task xxx reported error (0x80190194): The operation failed.
Troubleshooting:
1. First, please run following command to check the information of OAB Generation Server.
Get-Mailbox -Arbitration | where {$_.PersistedCapabilities -like “*OAB*”} | ft Name, Servername, Database
Example result as below:
2. Please make sure the authentication settings and URLs are set properly.
3. Try to verify whether the OAB files generated from MBX server successfully. Path as below:
C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\OAB\GUID folder
4. If all of the settings above set correctly, please try to check Autodiscover. Run “Test E-mail Autoconfiguration” to check whether there is anything abnormal on OAB. If has, please search the error code on MS official documents.
5. If this issue is related to local cache, please try to delete the OAB caches from local PC and re-download OAB for testing. Path as below:
C:\Users\Administrator.CU1(different)\AppData\Local\Microsoft\Outlook\Offline Address Books
[More information]
http://blogs.technet.com/b/exchange/archive/2012/10/26/oab-in-exchange-server-2013.aspx
http://blogs.technet.com/b/exchange/archive/2013/01/14/managing-oab-in-exchange-server-2013.aspx
Please click to vote if the post helps you. This can be beneficial to other community members reading the thread.

Hi Techy,
According to your description, I am still not quite sure about your environment. Could you please provide more information about it, such as:
1. How many Exchange servers in your coexistence environment? One Exchange 2010 with all roles and one Exchange 2013 with all roles? Or several Exchange 2010 and multiple Exchange 2013?
2. Are there two sites in your environment? What’s the Exchange deployment in different sites?
3. Please confirm if both Exchange 2010 and Exchange 2013 are Internet-facing.
Additionally, if you are using different namespaces for different services for internal access and external accessing, we need to include all service namespaces in your certificate with IIS service. Personal suggestion, we can follow ED Crowley’s suggestion
to use split-brain DNS in your environment and only use the same namespace for Exchange service URLs.
The following article described the details about how to configure different namespace for Exchange services by using Load Balance in Exchange 2013:
http://www.msexchange.org/articles-tutorials/exchange-server-2013/high-availability-recovery/introducing-load-balancing-exchange-server-2013-part2.html
Regards,
Winnie Liang
TechNet Community Support

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 Reverse dns setup

I recently migrated from SBS to Standard Windows servers with exchange 2013 and I'm having a heck of a time fighting spam. Mailflow is working fine, and we setup spam fighter exchange module which is catching most of the spam. However, it is missing some
that are spoofing our domain name with addresses that do and don't exist. I've read that the best way to stop this is to setup spf filtering and to do this you should setup reverse dns ptr records so you don't get blacklisted. The directions are rather confusing.
They say to setup a ptr record with your mail server's ip address. Here are my questions...
Do I have to set this up on both my dns and my service providers dns?
I currently have a A record and a ptr record pointing to the internal ip address on my internal dns server with the actual server name, but no records pointing to remote.domain.com.
Do I need to create additional A and PTR records using the External IP and remote.domain.com?
Right now my mx record points to mail.domain.com, but all of our connectors use remote.domain.com. Should the mx be changed to remote.domain.com?
Thanks for any help.

I've read that the best way to stop this is to setup spf filtering and to do this you should setup
reverse dns ptr records so you don't get blacklisted
Some antispam products to a reverse lookup on your IP address to make sure it matches the entry in the forward lookup zone. It does this to check that your server
is not spoofing the server name.
This won't necessarily prevent getting blacklisted (especially if you are sending spam), but it is definitely recommended for your mail architecture.
Do I have to set this up on both my dns and my service providers dns?
You will need to set this up on your Service Provider's DNS, as they will
technically own the IP address, and lease it to you.
Best practice is to have reverse lookup zones for your internal subnets in your internal DNS as well.
But this is not so much a spam related thing, as just a good idea.
Right now my mx record points to mail.domain.com, but all of our connectors use remote.domain.com.
Should the mx be changed to remote.domain.com?
This depends what these are used for. As you have come from an SBS environment, I'm guessing that both
of these names resolve to the same public IP address. If this is the case, you can leave the MX records as they are. If this is not the case, let me know and we'll discuss it later.
Let's say that you have a server called
mbx.contoso.com internally with an IP of
192.168.0.1. Externally, this server is known as mail.contoso.com
and has an IP address of 123.123.123.123.
In this case, you would do two things:
On your internal DNS server(s), create a reverse lookup zone for
192.168.0.0 and create a PTR record for
mbx.contoso.com with the IP of 192.168.0.1. This may already be done from when you set up Active Directory initially
Contact your ISP, and ask them to setup a
PTR record for mail.contoso.com for the IP
123.123.123.123

Create failover cluster to host Windows 2012 DC, Exchange 2013 and SQL as VMs

One of our clients has running Windows Essential 2012, SQL and exchange 2007 as VM on VMware for 4 years without major issue. However, the physical server is getting old and have some hardware issues recently. They have budgets to buy two Dell servers, EqualLogic
SAN, Windows server 2012 Datacenter and Exchange 2013. Is it possible for them to create failover cluster to host Windows 2012 DC, Exchange 2013 and SQL as VMs?
Bob Lin, MCSE & CNE Networking, Internet, Routing, VPN Troubleshooting on
http://www.ChicagoTech.net
How to Setup Windows, Network, VPN & Remote Access on
http://www.howtonetworking.com

We will move all VMs from VMware to Hyper-V. Thank you.
Bob Lin, MCSE & CNE Networking, Internet, Routing, VPN Troubleshooting on <a href="http://www.chicagotech.net">http://www.ChicagoTech.net </a>
How to Setup Windows, Network, VPN & Remote Access on <a href="http://www.howtonetworking.com">http://www.howtonetworking.com </a>

Exchange 2013 and Exchange 2010 coexistense

We have a and exchange 2010 organization with SP3 on most servers except for one 2010 CAS server that still requires SP1 for the purpose of legacy application compatibility. Can we introduce exchange 2013 in the org or will the setup detect
that there is an exchange 2010 server still with SP1 and fails to continue?

Hi,
For Exchange 2013 coexistence with Exchange 2010, the mininum version of Exchange server is Exchange 2010 SP3 on all Exchange 2010 servers in the organization. For more information about it, please refer to the Coexistence of Exchange 2013 and earlier versions
of Exchange server part in the article below:
http://technet.microsoft.com/en-us/library/jj898583(v=exchg.150).aspx
Personal suggestion, please upgrade your legacy application to the latest version which is supported with Exchange 2010 SP3 or higher Exchange version.
Regards,
Winnie Liang
TechNet Community Support

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.

Exchange 2013 and Outlook 2007

Is there a new way to connect EX2013 to Outlook 2007 SP3?
MSB

Hi Baker,
According to the description, I notice that you want to migrate from Exchange 2010 to Exchange 2013 and want to know how to connect Exchange 2013 with Outlook Client 2007.
Following is an article about the migration, for your reference:
Upgrade from Exchange 2010 to Exchange 2013
http://technet.microsoft.com/en-us/library/jj898583(v=exchg.150).aspx
Outlook client uses Autodiscover and Outlook Anywhere to connect to Exchange server, please make sure services’ URLs configured correctly.
If you want to communicate with external users, you need to apply a certificate issued from a Public CA.
After configuring all the points above, please run “Get-Mailbox –Identity allen | FL *GUID*” in EMS to get mailbox GUID of allen’. Input the GUID into server name filed.
More details on “Manual configuration guide for Outlook 2010 (Exchange 2013)” for your reference:
http://support.sherweb.com/Faqs/show/manual-configuration-guide-for-outlook-2010-exchange-2013
Disclaimer:
Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure
that you completely understand the risk before retrieving any suggestions from the above link.
Best Regards,
Allen Wang

Certificate configuring for exchange 2013 and office 365 hybrid deployment

Please advise on what digital certificate requirements for hybrid deployment and to configure it.

Hi sphilip,
If you want to deploy AD FS with Single Sign-On(SSO), we need use certificate to establish secure trust between on-premises Exchange 2013 and Office online.
We can use and configure a trusted third-part CA within all on-premises Exchange 2013 Mailbox and Client Access servers to ensure secure mail transport, more details about
Office 365 Hybrid Configuration Certificate Planning, for your reference:
http://blogs.technet.com/b/neiljohn/archive/2011/08/25/office-365-hybrid-configuration-certificate-planning-adfs-exchange-web-services-owa-oa.aspx
Best Regards,
Allen Wang

Exchange 2013 and exchange 2000

Hy guys...
I have this problem...i have a dommain controller x.com and i installed Exchange 2013 on it. I have another dommain controler
y.com with Exchange 2000. Thex.com dommain sends and receives mails from other Exchange 2013 servers but when it comes to
y.com dommaind i am only able to send emails to
[email protected] I cannot send emails from y.com
(Exchange 2000) tox.com (Exchange 2013).
Bothx.com dommain controller and y.com dommain controller are in the same network and i fave connectivity between them.
What might be the problem?
Than u,
M.S

Hi,
Firstly, it’s not supported to install Exchange 2013 and Exchange 2000 in the same organization and it’s not recommended to install Exchange server on Domain Controller.
http://technet.microsoft.com/en-us/library/ms.exch.setupreadiness.exchange2000or2003presentinorg(v=exchg.150).aspx
To understand more about the mail flow issue, I’d like to confirm your meaning that two DCs are in the same network.
If they are in the same forest, it’s by design that Exchange 2013 and Exchange 2000 cannot coexist.
For general mail flow troubleshooting , we can use telnet to check it.
For more information, you can refer to the following articles:
http://technet.microsoft.com/en-us/library/bb123686(v=exchg.150).aspx
http://msexchangeguru.com/2013/07/29/troubleshooting-mail-flow-issues/
Note: Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make
sure that you completely understand the risk before retrieving any suggestions from the above link.
If you have any question, please feel free to let me know.
Thanks,
Angela Shi
TechNet Community Support

Exchange 2013 and 2010 co-existance

We will have 2013 and 2010 exist together for a while...we plan to move away from using Unified Access Gateway for HTTP redirection to our Exchange services and implement Kemp
load balancers...two at our HQ site and two at our DR stie...
We plan to have a one arm configuration...from what I gathered...each load balancer will have a network connection and only one network connection and be on the same network as
our new Exchange 2013 servers. Can someone take a look at my config and give some input whether or not this will work and some suggestion on Ex13 urls, cert SAN names, etc.
HQKemp 2400 A
HQKemp 2400 B
DCKemp 2400 A        DCKemp 2400 B
172.16.1.104
172.16.1.105
172.25.1.104
172.25.1.10
Virtual IP   172.16.1.106
                         Virtual IP
172.25.1.104
From the video I’ve watched for Kemp install…we’ll create the following internal DNS records for the Exchange services that will be configured on balancers.
OWA/ECP
    mail.corp.local.com
              172.16.1.107
EWS               ews.corp.local.com
172.16.1.108
OAB               oab.corp.local.com
172.16.1.109
ActiveSync      mobile.corp.local.co
172.16.1.110
OA                 oa.corp.local.com
172.16.1.111
Autodiscover   autodiscover.corp.local.com 172.16.1.112
Question:
We will configure the Exchange services with these ip addresses linked to each service on all four load balancers?
Or will DR site load balancers have different IPs configured for same Exchange services?
Exchange services are split between our two sites…meaning Outlook Anywhere is configured for our CAS servers at our DR site and ActiveSync comes to HQ CAS servers as an example…so
I want all Exchange services to come through the newly installed load balancers at HQ and if they don’t respond…the Exchange services get redirected to the load balancers at our DR site.
Can you give some insight on the config of load balancers as to how we can do that?
I have a question about the cert we will have.
Our Microsoft rep says we should get a new wildcard cert…currently we have a UCC cert with the following SANs attached.
Will this new cert have to be installed on load balancers?
If so…can you suggest some ideas as to what new SANs I need if any of the new cert with Exchange 2010 and 2013 co-existing for a while.
Below are the SANs on our current UCC cert.
Outside resolvable SANs
Webmail.corp.local.com
205.223.19.25           portal.corp.local.com     205.223.27.78
Portal2.corp.local.com
205.223.19.25
Autodiscover.corp.local.com
205.223.19.25
Internal SANs
Hqcas1.corp.local.com
Hqcas2.corp.local.com
Dccas1.corp.local.com
Dccas2.corp.local.com
Owamail.corp.local.com
(this CAS Array server name that HQ CAS servers create)
What do you suggest we use for the external urls on Exchange 2013 for these services?
Our firewall guy says we’ll use same names,
but I’m not sure if we try to use same name if we’ll get an error?
Active Directory may say name already in use?
We plan to have firewall to just redirect requests for external urls to load balancers…sound correct?
Meaning load balancer won’t have an external NIC defined…which makes it a one arm config…correct?

Hi Techy,
According to your description, I am still not quite sure about your environment. Could you please provide more information about it, such as:
1. How many Exchange servers in your coexistence environment? One Exchange 2010 with all roles and one Exchange 2013 with all roles? Or several Exchange 2010 and multiple Exchange 2013?
2. Are there two sites in your environment? What’s the Exchange deployment in different sites?
3. Please confirm if both Exchange 2010 and Exchange 2013 are Internet-facing.
Additionally, if you are using different namespaces for different services for internal access and external accessing, we need to include all service namespaces in your certificate with IIS service. Personal suggestion, we can follow ED Crowley’s suggestion
to use split-brain DNS in your environment and only use the same namespace for Exchange service URLs.
The following article described the details about how to configure different namespace for Exchange services by using Load Balance in Exchange 2013:
http://www.msexchange.org/articles-tutorials/exchange-server-2013/high-availability-recovery/introducing-load-balancing-exchange-server-2013-part2.html
Regards,
Winnie Liang
TechNet Community Support

FIM Synchronization Repeat Contacts Exchange 2013 and 2010

Hey how are you?
actualemnte story with FIM
Synchronization 2010 R2
I have two organizations:
Oraganizacion 1:
Exchange 2013 S1
FIM Server
organization 2
Exchange 2010 Sp3
contacts organization number two
is possible to see them in organizavion
number one
the downside is trying to sincornizar
repeatedly contacts the organization towards each
organization's number two being
repeated and causes problems with users.
repeated contact:
contact.dominio.com
contact1.dominio.com
contact3.dominico.com
I can do ??

Hi Dominik,
thanks for pointing number 2 out :)
For my Problem on the Exchange:
I get the Event ID 12 in the Application log with:
The Forefront Identity Manager Service cannot connect to the Exchange Web Service.
In the FIM Log I find:
System.Web.Services: System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote
host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
This leads me to
http://social.technet.microsoft.com/Forums/en-US/7697048b-3cf1-48ce-a8eb-b5c51104c279/error-connecting-to-exchange-2010?forum=ilm2 . This guy seems to have the same error. But I don't know exactly what he changed in IIS. As a said, my Certificate chain
is OK.
Do you have some resource for me, where to start to get rid of this?
Thanks a lot,
Martin
www.sccmfaq.ch

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
My Linkedin Profile
My MVP Profile

Exchange 2013 and DNS Round Robin downside?

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