I am going to be going to Check out a client\server network and was wondering what some of the first things are that i should look at?

He was talking about small errors and certain clients not being able to connect. I did some college studies on networks and so on, so my knowledge is there but i have never had to do any looking at devices in the real world yet and this could be very important.

Thank you in advance!

3 Answers 3


For the "clients not being able to connect" issues I would use the the OSI model...

  1. Check physical connectivity, are the cables properly connected, are the network cards operational?
  2. Check ARP table...can you see MAC adresses?
  3. Check IP settings, is the routing properly setup? Are people experiencing these issue able to connect on the server? (using ping, traceroute, telnet...) at this level, it can be a firewall issue as well.
  4. Check if packets are rejected because of errors? When doing telnet, are you able to connect but the connection is droped with error message?
  5. Check if you need to be connected to a VPN to access this server?
  6. Check if traffic is encrypted, if you need a VPN, is the VPN encrypting packets properly?
  7. Check for software configuration issues.

I hope I didn't screw up on the Layer/Operation match...

Obviously, if the client is able to browse or if they are already able to "use" the network, it's obviously not an issue at the first layer.

But, I did experience long troubleshooting window with lots of competent people on the line trying to fix an issue...only to realise the cable was plugged in the wrong NIC.

In a nutshell, this should be the way to troubleshoot most networking issues, that's why it's the one thing that all networking books and certifications put in the first or second chapters.

  • Thank you, i like how you touched bases on the layers and not on certain subjects directly. This was a lot of help, thank you! Dec 6, 2011 at 16:24

Depends what the errors are revolving around, but if its a check up on the health of the network I'd probably look at if any packets are getting dropped, any collisions, bottle necks, throughput.

Aside from that there's always checking for broken cables and damaged faceplates.


Check the event logs on the domain controllers. Run stuff like DCdiag, etc to see if anything flags as not functioning properly.

  • thank you also, these are some that i hav enot thought about yet! Dec 5, 2011 at 16:46

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