Multi IP Problem: DNS Server Can't Resolve Hosts

[Artimedia]

Before someone asks, I did use the search function before posting. None of the replies I found applies to my situation or helped me solving it, thus my post here.

I have setup my new Qnap TS-659 Turbo and want to use the two Lan Ports in Multi-IP setting. I attached Lan #1 to one Laptop where I installed Qnap Finder. I also installed the firmware updates from there. To Lan #2, I attached a Switch (HP V1405C-5G) which controls a LAN with 3 Workstations (plus the Qnap, of course). So, for now, neither Lan #1 nor Lan #2 have internet connection.
I am using DHCP both Lans. All workstations are using DHCP, as well as the Laptop and Qnap.

Setup01.jpg

Question #1: When I enter the Administration GUI, I get the error: "Your DNS server can't resolve hosts, and some applications might not work properly". I noticed that on "System Administration > Network > TCP/IP", both Ethernet Ports have the same IP. Is this supposed to be this way??...

Only their MAC Addresses are different: 00:08:9B:BF:DE:24 and 00:08:9B:BF:DE:25, respectively...

Question #2: I also noticed that every time I restart my workstations, my Lan #2 looses all 3 workstations and I have to restart the switch. After restarting the switch, all my workstations become visible again BUT... Lan #1 stops working (I stop being able to access the Qnap). Vice-versa is also true: As soon as I remove my Lan #1 cable from my laptop and attach it again, I recover connection with Qnap, but then I loose Qnap connection with Lan #2 again. What may be causing this??...

Question #3: Are there any advantages in using Static IP in a configuration such as mine? Would it solve any of these issues?

Question #4: Should I activate DDNS or IPV6?..

Here are some screenshots of my settings:

settings-Ethernet01.jpg

settings-Ethernet02.jpg

Thanks in advance for your help!

Note: This is perhaps not very important for now but, soon enough I will be using Lan #1 Port for a different purpose: Wired Internet connection through a Router (Netgear WNDR3700). If there are any important setttings regarding IP settings that I must now for that, please tell me.

[Artimedia]

Ok, after banging my head all night against Google and networking forums, I think I figured a good part of this problem out:

Static IP manual configuration was the solution for Lan #2 and all the 3 workstations in that network. This way, I can now restart my workstations or Qnap as many times as I want, apparently without ever loosing any functionality of my Lan #2 network. That has been solved. It didn't make sense to have them in DHCP because the Switch does not generate IPs and has no DHCP so the IPs of the workstations were being changed and unrecognized by the switch and the network everytime the workstatiosn/Qnap were rebooted.

All it took was some reading and I was easily able to setup my Lan #2 with manual IP/Subnet Mask settings successfully.

About the "DNS Server Can't Resolve Hosts" error message, I still get it... Probably because I still have Lan #1 in DHCP mode. Maybe I need to put it under static mode, at least untill I'm using it to connect to my laptop. Maybe this won't be a problem once I connect Lan #1 to the Router (for Internet access), since at that point, the Lan #1 IP wil be generated by HDCP by the Router.

I'll let you know about that.

However I have a new "problem" now: When I check out my network places on my Laptop, instead of seeing only the Qnap (through the Lan "1 connection), I am now seeing the Qnap AND all the workstations that are connected to the Qnap through Lan #2!.. How come???
I mean, I can't really connect to them. When I try to double click on them, it says "Windows cannot access \\Workstation01" it also says "the path cannot be found"... But, how come I can see them if they are from a different Lan/network with a different IP and a separate Ethernet port?

[schumaku]

First thing that is likely wrong: The two network must reside in two different TCP/IP subnets, obvious in this case, the LAN1 and LAN2 interfaces cannot have the same IP address therefore. Because of the two interfaces are configured actually in the same subnet, the NetBIOS broadcasts will pass the NAS, making the systems on the other network visible. -> You must configure two different TCP/IP subnets for the two LAN.

Remembering from your previous posts, the system one network are intentionally isolated, and are not supposed to reach the internet, while the other network is connected to a router to reach the rest of the world. -> Set the default gateway pointing to this network interface.

The problem for the NAS with two interfaces pointing to two physically different networks with the same TCP/IP addresses: The network stack has no information, which one to use - so the outgoing traffic can be randomly distributed, and this can lead to several more issues you have not experienced yet.

That should do the job then.

Regards,
-Kurt.

[Artimedia]

Thanks Kurt! However what I found strange was that I can still see the devices on Lan #2 through Lan #1 (see image in first post), even after having configured Lan #2 IP manually according to the below images.

settings-Ethernet02-Manual.jpg

I must point this out: Lan #1 is going to be used to connect to a router to access internet, as you saw in my other topic. For that reason I have left Lan #1 in DHCP mode for now because my ISP only provides Dynamic IPs... And that way, I will let the router act as my DHCP server.
Presently however, I have only my Laptop NIC attached directly to the Qnap. Can it be that, because I have both the Qnap and the Laptop configured to HDCP, without any of them acting of HDCP server, this is causing Lan #2 to be visible???... If so, why would that be?

Obviously, this is why I still get the "DNS Server Can't Resolve Hosts" error but, is it possible that this is also related to why Lan #1 can see Lan #2?..

[leliep]

Did anyone notice that after configuring the network parameters on NAS systems with 2 NICs the local hosts file (/etc/hosts) contains ambiguous information, because the hostname of the system appears twice with two different IP addresses?

Code: Select all

[~] # cat /etc/hosts
127.0.0.1 localhost       localhost
10.10.10.58     px58.domain.de        px58
10.10.200.58    px58.domain.de        px58

If both NICs belong to different subnets, this might lead to connectivity problems and wrong DNS entries. So you have to manually change the hostnames for one of the entries. I think this needs to be corrected in the WEBGUI...

Pls. see also http://support.microsoft.com/kb/177075/en-us

[onlyalex]

Wan1 Modem --> Router1 --> Switch1 --> Nic1 192.168.0.X / 255.255.255.0 on Qnap

Wan2 Modem --> Router2 --> Switch2 --> Nic2 172.16.0.X / 255.255.192.0 on Qnap

Using an class C subnet for nic1 and class B subnet for nic2 you can provide access to the Qnap device from both lans and still keep them separated. Note: Only one default gateway can be used.

Cheers

[schumaku]

If both NICs belong to different subnets, this might lead to connectivity problems and wrong DNS entries.

Why? DNS entries and static entries in /etc/hosts have absolutley no relation.

So you have to manually change the hostnames for one of the entries. I think this needs to be corrected in the WEBGUI...

Not mandatory. If you desperatly want, you could name the two _interfaces_ individually. Hoever, in reality: How often do you need to resolve from the inteface name to the IP address - based on a static host configuration - of a specific interface from the NAS?

Nothing of all that is required to make or break DNS server lookups!

1. The NAS does out of the box not connect (ie. brige [L2] or router [L3]) the two LAN interfaces. However, if the two interfaces are in the same TCP/IP subnet (what must not happen at all!), you never know which interfce is used for the return traffic.
2. The NAS can have ONLY ONE active default gateway on one interface. So it will not be able to resolve (nor use the second Internet connection). DNS might work when only the router LAN IP are listed in DNS, but not when ISP or generic use DNS servers are configured: Because of this traffic will never go out to the non-gateway interface - and ISP DNS might not answer to requests from another ISP name requests.

[leliep]

If both NICs belong to different subnets, this might lead to connectivity problems and wrong DNS entries.

Why? DNS entries and static entries in /etc/hosts have absolutley no relation.

So you have to manually change the hostnames for one of the entries. I think this needs to be corrected in the WEBGUI...

Not mandatory. If you desperatly want, you could name the two _interfaces_ individually. Hoever, in reality: How often do you need to resolve from the inteface name to the IP address - based on a static host configuration - of a specific interface from the NAS?

Nothing of all that is required to make or break DNS server lookups!

Thanks for your reply. You are confirming what I also have been thinking. But because we have problems with the name resolution of the two TS-809U-RP NAS systems, we are looking into the details trying to understand what's really happening and found the aforementioned issues, which might or might not contribute to our problem.

Here are some more information about the problem:

Both of the NAS systems connect with one NIC into the LAN (10.10.11.0/24) where also the NAS clients exist, the secondary NICs of both NASes are connected with a separate vlan for data replication purposes between the NAS systems. This vlan is in a separate subnet (10.40.205.0/24), which is not accessible by the NAS clients.

All IP addresses of the NAS systems are static.

The Microsoft DNS server has two separate entries for each of the NAS systems:

• nas1 (10.10.11.101)
  nas1-sync (10.40.205.101)
  nas2 (10.10.11.102)
  nas2-sync (10.40.205.102)

From time to time the DNS server mysteriously has additional name record entries for the NAS servers:

• nas1 (10.10.11.101)
  nas1 (10.40.205.101)
  nas1-sync (10.40.205.101)
  nas2 (10.10.11.102)
  nas2 (10.40.205.102)
  nas2-sync (10.40.205.102)

We have yet no idea about who or what is generating these ambiguous DNS entries.
Obviously they are generating problems accessing the NAS systems by their DNS names, as you can imagine.

[schumaku]

Nothing of all this is really related to why your NAS is not able to resolve hosts as shown in the subject - or I am missing the point now.

We have yet no idea about who or what is generating these ambiguous DNS entries.

From what I'm aware of, the NAS does not push dynamic DNS name updates - so it's not able to change the name on your "real" DNS. However: Windows does mix-up DNS and Windows naming schemes. I guess hhis is why you see the "faux" entries with the effective hostname.

[leliep]

Nothing of all this is really related to why your NAS is not able to resolve hosts as shown in the subject - or I am missing the point now.

We have yet no idea about who or what is generating these ambiguous DNS entries.

From what I'm aware of, the NAS does not push dynamic DNS name updates - so it's not able to change the name on your "real" DNS. However: Windows does mix-up DNS and Windows naming schemes. I guess hhis is why you see the "faux" entries with the effective hostname.

Maybe I should have entered my contribution as a new string, to avoid confusing two different issues, sorry. Anyway, here we go...

The point is that in our case the clients who want to access the NAS cannot use it when the "real" MS DNS server has duplicate name records with two different IP addresses. Some NAS accesses (FTP) do not work at all, some (web file mgr) seem to be very slow (probably due to ~50% of the requests trying to access the wrong ip address). When we delete the duplicates from the DNS server, everything is gonna work again.

So the problem that we are trying to solve is: how or by which mechanism does the "real" DNS server receive the additional, duplicate NAS name records with the ip address of the secondary NICs and how can we stop this? Maybe we should try to capture the network traffic to find out who's the culprit. Up to now for me it looks as if the NAS _does_ push DNS name updates, somehow (which would make sense in a dhcp scenario, but we're using static ip addresses)...

BTW: no, "Automatically register in DNS" has _not_ been activated in "Microsoft Networking/Advanced Options".