Issue with windows 2012 server network or internet connectivity

Chopper2302
Chopper2302 used Ask the Experts™
on
Hey all,

I have a wierd one here.. I have a client running 2012 R2 - this runs their file & print sharing, Active Directory and backup software. The IT officer that I deal with has been asking me to help him with an issue, which is the server goes offline and has no connectivity. The server remains on and the OS is in tact but the network card says "no internet" unidentified network.

DHCP is running through the firewall which is 192.168.8.254 (Default Gateway / DHCP). Long story but we will leave that.. This firewall is around 8 years old btw so it could be the culprit and will be providing them with a test unit to see if we can narrow down but I haven't given you the curve ball yet.. wait for it.

Things we have tried;
  • Checked error logs at the time it drops and nothing pops up at the time of the drop out.
  • Testing all cables running from server, Tested OK.
  • Tested connecting to the Firewall LAN port, tested OK.
  • Swapped NICS from NIC4, to NIC3, NIC2 on the server and still no go.
  • Checked all the IP config is ok. 192.168.8.11 (server) / 255.255.255.0 / 192.168.8.254 (gateway) / 127.0.0.1 (DNS)
  • From a client's computer, provided a static IP address. Cannot connect to server or gateway so it does not see the network at all which is odd
  • We have swapped out to a new switch as a test which we will leave there for the time being
  • Checked DNS services, forwarders & entries are correct on the server
Yes the curve ball.. so my client has a MAC Book. It seems now that every time he connects his MAC book, the server connection comes alive, then the computers all come back online too.

We have tested over 4 times now and when he disconnects his MAC, the server goes offline within 10 mins, everytime! When he connects, the server comes online again.

When he connects to the network, he receives the 1st IP address given from DCHP (192.168.8.50). When he configures a static IP address from his MAC, he connect connect

I am waiting for the go ahead for me to drop the firewall in but are there any other suggestions or troubleshooting I should be looking at b/c I am stumpped.
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JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
See what a new firewall brings (8 years is a long time for a constant use firewall).

Also DHCP should be on your server along with DNS. Works vastly better.  Get a consultant to set this up if you need help.
Top Expert 2016

Commented:
use wireshark or other packet tracer and connect / disconnect the MAC, sounds like it is the culprit

Author

Commented:
Thanks for your responses.

use wireshark or other packet tracer and connect / disconnect the MAC, sounds like it is the culprit

Do you think I should be doing this from the server?

Also, any tips on what I should be looking for.. I've rarely used Wireshark.
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JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
Do you think I should be doing this from the server?

If you wish to try Wireshark (I use CommView myself), then yes, try on the server.
MaheshArchitect
Distinguished Expert 2018

Commented:
Yes the curve ball.. so my client has a MAC Book. It seems now that every time he connects his MAC book, the server connection comes alive, then the computers all come back online too.

where you connect the MAC and how it is related to domain controller which don't having internet?

Somewhere you said that DC is pointing to loopback address as DNS..
DNS should point to own IP (192.168.8.11) instead of loopback

Default gateway is nothing but internet gateway which is the way to go to external world for DC, but how name resolution is working
did you configured public dns servers (say 8.8.8.8) as dns forwarders on DNS server properties \ forwarders tab?
hecgomrecNetwork Administrator

Commented:
If any computer in a given network is able to communicate among themselves using either IP or DNS but have no access to the "Cloud" (Internet) then your gateway is the one to blame.  If you can't resolves names then DNS server.

Seems odd but looks like somehow your server is not configured properly to connect outside the network.  I will reset the NICs and set them up again.

If you don't have DNS and DHCP on your server, then you should have it set it up too... then your gateway must point to the router that connects to the "cloud", what ever that device is... even if it is 15 years old, a home router, small business... whatever!!!

if you want to see what's going on and where things are going.... plug the MAC and from the Server run:  tracert google.com .  Check which nodes are involved and troubleshoot accordingly.

Good Luck!!!
Scott SilvaNetwork Administrator

Commented:
Also.. An AD server should really have a fixed IP address and not a DHCP assigned one... Just best practice...
I'm missing a couple of basic diagnostic steps here:

What is different in ipconfig /all (on the server) between when it works and does not?

When the server is not connecting, can it ping 192.168.8.254?  What about 4.2.2.2?  Lastly, google.com?
hecgomrecNetwork Administrator

Commented:
IPCONFIG /ALL will show all NIC on the machine.

TRACERT will display where the package is forwarded to next hop.

IPCONFIG will also show changes/confirm to you if there any change when the MAC is/not present or connected.

Author

Commented:
Yes, I have configured a static IP address for the server (192.168.8.11) and have set this as the primary DNS server also.

I will try doing a tracert when the MAC and see where the packets go.

Once I go on-site (after the new firewall install) & the issue is still there, I will gather as much information as possible.

Thanks for your input all.
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
Also when you get there, move DHCP and DNS to the Server.  That is essential

Author

Commented:
Been meaning to write back to this one.. sorry for the late response.

The issue was caused by a faulty dock used for a Mac computer. I only found this out by looking at the activity of all the ports on the switch. I ended up finding out that the port linked to the dock was blinking out of control compared to all the other ports. When we removed this from the equation, all returned to normal.

The next step in my fault finding was to remove all network cables from the switch and insert one-by-one to see if there were any faulty devices on the network.

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