Nslookup: DNS request timed out. time out was 2 seconds. (When the primary DNS is down)

Question

Hi All,
I have set up 2 Windows Server 2012 domain controllers (DCA & DCB). DCA points at DCB as the primary DNS, and itself as the alternate DNS. DCB points at DCA as the primary DNS, and itself as the alternate DNS.
When both DCs are running and if I do an nslookup on DCA: The result is as follows:
Default Server: dcb.testdomain.com
Address: 30.30.30.2
nslookup on DCB:
Default Server: dca.testdomain.com
Address: 30.30.30.1
Client PC (Windows 7 Pro):
1st DNS : 30.30.30.31
Alternate DNS: 30.30.30.32
nslookup on the client PC
Default Server: dca.testdomain.com
Address: 30.30.30.1
Up to here everything is fine. Now if I turn off DCA, and do an nslookup, the result is as follows:
DCB nslookup:
DNS request timed out.
       time out was 2 seconds.
Default Server Unknown
Address: 30.30.30.31
Client PC nslookup:
DNS request timed out.
       time out was 2 seconds.
Default Server Unknown
Address: 30.30.30.31
I waited for more than 15 minutes an tried again, it didn't help.
I have been reading a few similar posts on this matter, but couldn't find the answer.
I would  expected it to display the DCB when I do an nslookup.
Question 1: Shouldn't that display DCB rather than displaying a time out message when I do nslookup?
Question 2: The fact that it displays a time out message, does it mean that more configuration needs to be done? If so please kindly advice what needs to be done. 
I did an ipconfig /displaydns command. I realized that the order of DNS have changed on both DCB and the Client PC:
Now, they both display DCB on the top of the list, whereas they were displaying DCA on the top of the list prior to the shut down.
Question 3: Does it mean that the Client PC now knows that the 1st DNS is down and so it's using the 2nd DNS?
If so, why does the nslookup display the time out message?
Question 4: Is it possible to configure either of DNS Server or the DNS client, so it displays the 2nd DNS when the first DNS is not accessible and when I do nslookup?
Thank you for. 

Answer 1

Hi Ton_2013,
Based on my understanding, the issue we are experiencing is that: when the primary DNS server is down, the result of the tool Nslookup is to diaplay the time out message at first. Right?
Based on my knowledge, timed out message is means that the server did not respond to a request after a certain amount of time and a certain number of retries. Because the primary DNS server is down, it can't respond to this request and time is out. When
the primary DNS server can't respond, the secondary DNS server works to ensure effective work. And the order is changed as you said.
As to the reason why the result is still the same even when the order has changed, we can try to use Network Monitor to capture network traffic and view and analyze it to find the cause. And the cause may be the cache. For your information, please refer
to the following link to download the tool Network Monitor:
http://www.microsoft.com/en-hk/download/details.aspx?id=4865
Regards,
Lany Zhang