DNS Update Issue
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@scottalanmiller said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@scottalanmiller said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The server cannot point to itself. DNS servers have forwarders, it's a different concept.
It can, it's just a terrible idea. This was the case with my families business.
That'll definitely break all kinds of things.
Yeah I immediately changed it. One of the DC's had no forwarders at all!
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@wirestyle22 said in DNS Update Issue:
@scottalanmiller said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@scottalanmiller said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The server cannot point to itself. DNS servers have forwarders, it's a different concept.
It can, it's just a terrible idea. This was the case with my families business.
That'll definitely break all kinds of things.
Yeah I immediately changed it. One of the DC's had no forwarders at all!
This is actually less of an issue. Windows DNS servers have root hints - so if there are no forwarders listed, the query will be sent to a root server.
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@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The DNS server (via DNS Manager) should have it's forwarders set to whatever service you want to use as your upstream resolution provider (I use Google - some people pay Umbrella, so they use Umbrella).
ok, weird. One of my DC's, the one at my location, is set to only google. The other at my branch is set to the DC at my location, then our two ISP provided servers, and then finally to google.
You DNS Forwarders are set to only google? ok - so what's the problem? There is nothing wrong with that.
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@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The DNS server (via DNS Manager) should have it's forwarders set to whatever service you want to use as your upstream resolution provider (I use Google - some people pay Umbrella, so they use Umbrella).
ok, weird. One of my DC's, the one at my location, is set to only google. The other at my branch is set to the DC at my location, then our two ISP provided servers, and then finally to google.
You DNS Forwarders are set to only google? ok - so what's the problem? There is nothing wrong with that.
He has another that is set internally
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@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The DNS server (via DNS Manager) should have it's forwarders set to whatever service you want to use as your upstream resolution provider (I use Google - some people pay Umbrella, so they use Umbrella).
ok, weird. One of my DC's, the one at my location, is set to only google. The other at my branch is set to the DC at my location, then our two ISP provided servers, and then finally to google.
You DNS Forwarders are set to only google? ok - so what's the problem? There is nothing wrong with that.
It's that both my DC's are different, that's the weird part.
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So thought experiment:
If DC1 and DC2 have 127.0.0.1 as their only DNS entry and their forwarders are only set to each other, how does that resolve? Can the DC's tell the difference between a forwarding request and a normal DNS request? Otherwise wouldn't this time out?
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@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The DNS server (via DNS Manager) should have it's forwarders set to whatever service you want to use as your upstream resolution provider (I use Google - some people pay Umbrella, so they use Umbrella).
ok, weird. One of my DC's, the one at my location, is set to only google. The other at my branch is set to the DC at my location, then our two ISP provided servers, and then finally to google.
You DNS Forwarders are set to only google? ok - so what's the problem? There is nothing wrong with that.
It's that both my DC's are different, that's the weird part.
That was just someone not knowing what they were doing. it would be awesome if DNS replicated that setting as well - but I'm sure there are reasons to not do that.
i.e. using an IP of a local forward lookup based on region. -
right, but I wonder if my branch DC should be pointing to the HQ DC, or just going straight to external?
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@wirestyle22 said in DNS Update Issue:
So thought experiment:
If DC1 and DC2 have 127.0.0.1 as their only DNS entry and their forwarders are only set to each other, how does that resolve?
It doesn't. The local system doesn't know about other domains so there would be either no response or a failure response. But really it would also result in an infinite loop.
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@Dashrender said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
So thought experiment:
If DC1 and DC2 have 127.0.0.1 as their only DNS entry and their forwarders are only set to each other, how does that resolve?
It doesn't. The local system doesn't know about other domains so there would be either no response or a failure response. But really it would also result in an infinite loop.
Right which would timeout.
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@Donahue said in DNS Update Issue:
right, but I wonder if my branch DC should be pointing to the HQ DC, or just going straight to external?
AD Integrated forwarders should NEVER point toward internal sources like that.. their purpose is to get information about domains it does not know about. AD integrated forwards have all of the local data on all DNS servers. There would be nothing to gain by sending to another internal DNS server. They should make their request to an outside, upstream source.
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I just did an experiment and disabled the NIC on my HQ DC. DNS is still able to resolve like normal, so I assume things are fine there. I will check the branch too. For some reason we recently had issues with one DC being down, and DNS being down too, as if it didnt failover to the other DC.
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@wirestyle22 said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
So thought experiment:
If DC1 and DC2 have 127.0.0.1 as their only DNS entry and their forwarders are only set to each other, how does that resolve?
It doesn't. The local system doesn't know about other domains so there would be either no response or a failure response. But really it would also result in an infinite loop.
Right which would timeout.
Exactly - which is what you saw happening, I believe.
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@Donahue said in DNS Update Issue:
I just did an experiment and disabled the NIC on my HQ DC. DNS is still able to resolve like normal, so I assume things are fine there. I will check the branch too. For some reason we recently had issues with one DC being down, and DNS being down too, as if it didnt failover to the other DC.
Was DHCP handing out two DNS servers? was the second DNS server online and working?
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@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
I just did an experiment and disabled the NIC on my HQ DC. DNS is still able to resolve like normal, so I assume things are fine there. I will check the branch too. For some reason we recently had issues with one DC being down, and DNS being down too, as if it didnt failover to the other DC.
Was DHCP handing out two DNS servers? was the second DNS server online and working?
DHCP hands out the local DC first, then the remote DC. During this outage, that also went down because it was the same DC VM. But at the time, that wasnt my primary concern. now that everything is working, I feel the need to verify that all aspects will failover correctly. DNS apparently does but I am not sure if all other DC functions do.
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@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
@wirestyle22 said in DNS Update Issue:
@Donahue The first one (It's own IP) should be 127.0.0.1 is what they are saying
That's what I thought. What about settings for the DNS server service?
The DNS server (via DNS Manager) should have it's forwarders set to whatever service you want to use as your upstream resolution provider (I use Google - some people pay Umbrella, so they use Umbrella).
ok, weird. One of my DC's, the one at my location, is set to only google. The other at my branch is set to the DC at my location, then our two ISP provided servers, and then finally to google.
You DNS Forwarders are set to only google? ok - so what's the problem? There is nothing wrong with that.
It's that both my DC's are different, that's the weird part.
Yeah, that's not idea. Whatever is good for the gander is good for the goose.
Where gander is DC1 and goose is DC2 for no particular reason.
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yeah, its changed now. That was setup by some random third party when our AD was setup years ago, at the time I didnt even know what DNS was.
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@Donahue said in DNS Update Issue:
@Dashrender said in DNS Update Issue:
@Donahue said in DNS Update Issue:
I just did an experiment and disabled the NIC on my HQ DC. DNS is still able to resolve like normal, so I assume things are fine there. I will check the branch too. For some reason we recently had issues with one DC being down, and DNS being down too, as if it didnt failover to the other DC.
Was DHCP handing out two DNS servers? was the second DNS server online and working?
DHCP hands out the local DC first, then the remote DC. During this outage, that also went down because it was the same DC VM. But at the time, that wasnt my primary concern. now that everything is working, I feel the need to verify that all aspects will failover correctly. DNS apparently does but I am not sure if all other DC functions do.
If DNS fails over, then AD should as well, though you could have some timeout issues... which will mostly be masked from the users by slowness.
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@wirestyle22 said in DNS Update Issue:
So thought experiment:
If DC1 and DC2 have 127.0.0.1 as their only DNS entry and their forwarders are only set to each other, how does that resolve? Can the DC's tell the difference between a forwarding request and a normal DNS request? Otherwise wouldn't this time out?
The problem here, is if you are on DC1 and DC1's DNS fails, then the loopback lookup will have nowhere to go. And everything will fail, even though you have redundant services on your network.
If you had DC2 as the secondary DNS entry, things would have kept working.
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@Donahue said in DNS Update Issue:
right, but I wonder if my branch DC should be pointing to the HQ DC, or just going straight to external?
Branch DC's DNS should point first to the loopback, then to the HQ DNS. That way to minimize WAN traffic, and maximize performance.
