Has anyone had a problem setting up LBFO with LACP where DNS resolution to even local resources stops working? I am experiencing this issue.
I have LBFO configured on my Windows Server 2012 with LACP and Address Hash. I have two NICs in the LBFO team each connected to a different switch that I am told by the Network group is configured as a single logical switch. (Since LACP is switch dependent). Starting out, DNS resolution works fine. After a day or so, sometimes within minutes, DNS resolution to even local resources either time out or is extremely slow. If I disable one of the NICS in the LBFO team, DNS resolution works fine immediately. If I re-enable the NIC where both are enabled, DNS times out or is slow to resolve. If I delete the LBFO and reconfigure, DNS works for a little while but eventually malfunctions again. If I disable the LBFO interface and re-enable, DNS resolution works again. Both NICS are on the same VLAN behind an BigIP LTM with a single VIP.
The LTM does not act in anyway as a firewall. What is weird is that if I see the malfunction with DNS resolution, all I have to do is disable one NIC in the team and DNS works fine. Re-enabling the NIC immediately brings back the problem. It does not matter which NIC of the team I disable. I contacted our Network team to inquire about the fact that LACP is switch dependent but I was told that the switches operate as a single logical switch and thereby meets the switch dependent criteria. We currently have other servers on LACP using Hyper-V rather than Address Hash and there are no problems. But my server is not a Hyper-V server. Can anyone help?
Please check if there are duplicate records in DNS server.
Also someone found two entries of default gateway in route table cause DNS issue:
Bug in NIC Teaming Wizard makes Duplicate Default Routes in Server 2012
In addition, you can check the log to see if any errors.
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Hope this helps.
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- Edited by Daniel JiSunMicrosoft contingent staff, Moderator Wednesday, October 16, 2013 2:16 AM
Thanks for that answer but the bug found does not relate to my situation. I am using two network adapters and neither have had a static IP or gateway defined at any time. it is stated in the article above that this problem is exhibited when defining a team with one adapter, or when the gateway is defined on the physical adapter and then on the virtual one resulting in two gateways. I do not have two gateways when I run route print.