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when the devices go offline, can you do a nslookup and see dns is working Ok. <br />
Its not DHCP for sure.
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when the devices go offline, can you do a nslookup and see dns is working Ok.
Its not DHCP for sure.

<div>
Also make sure you have fewer devices (by 2 or 3) than your DHCP scope.
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Also make sure you have fewer devices (by 2 or 3) than your DHCP scope.

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Hi John. &nbsp;I think my device count probably does exceed the DHCP scope, so that's something that might be a problem. &nbsp;I would assume that the excess devices would simply just not get an IP and not affect the network adversely. Is that not the case? &nbsp;And for the nslookup, what command could I issue to test the DNS thru nslookup? &nbsp;anything at all, or something specific?<br />
<br />
thanks
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Hi John.  I think my device count probably does exceed the DHCP scope, so that's something that might be a problem.  I would assume that the excess devices would simply just not get an IP and not affect the network adversely. Is that not the case?  And for the nslookup, what command could I issue to test the DNS thru nslookup?  anything at all, or something specific?

thanks

<div>
Look in the DHCP lists in the servers. That should tell you.
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Look in the DHCP lists in the servers. That should tell you.

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sounds like your having a NIC problem
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Miftaul - I just noticed you're saying &quot;It's NOT DHCP for sure?&quot; &nbsp;So you don't think this is being caused by DHCP at all - but DNS possibly. Do I understand you right?<br />
<br />
thanks
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Miftaul - I just noticed you're saying "It's NOT DHCP for sure?"  So you don't think this is being caused by DHCP at all - but DNS possibly. Do I understand you right?

thanks

<div>
the problem seems to have gone away. so I'm going to close this out. &nbsp;thank you!
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the problem seems to have gone away. so I'm going to close this out.  thank you!

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@Damian_Gardner &nbsp;- Thanks for the update and I was happy to help.
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@Damian_Gardner  - Thanks for the update and I was happy to help.

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<div class="content wysiwyg-content">
Hello - we are experiencing weird behavior from our Windows Server 2008R2 LAN &nbsp;- some servers lose access to the Internet but are still accessible to the local network, and at times ALL servers and services drop off the network, but come back in 5-10 minutes time. &nbsp;So we're wondering if this is somehow caused by DNS or DHCP or possibly a combination of things. &nbsp;Just starting our investigation and looking for any help we can get.<br />
<br />
thanks
</div>
</div>


Hello - we are experiencing weird behavior from our Windows Server 2008R2 LAN  - some servers lose access to the Internet but are still accessible to the local network, and at times ALL servers and services drop off the network, but come back in 5-10 minutes time.  So we're wondering if this is somehow caused by DNS or DHCP or possibly a combination of things.  Just starting our investigation and looking for any help we can get.

thanks

Can DHCP cause network anomalies?

The Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks and an extension of the Bootstrap Protocol. DHCP allows for computers to be configured automatically to communicate with each other over an IP network without the need for manual setup by a network administrator. The implementation of DHCP relies on a DHCP server to hand out network configuration information to DHCP-capable clients that request an IP address (and other information required or useful in communicating with other devices on an IP network). In addition to an IP address, common configuration information served over DHCP includes a default gateway, subnet mask and DNS sever(s).

DHCP

Network analysis is the process of identifying and remediating the processes and systems within a network, including performance, connectivity and security. The process is performed through the use of tools developed for monitoring and analyzing network activity. Network problems that involve finding an optimal way of doing something are studied under the name combinatorial optimization. Examples include network flow, shortest path problem, transport problem, transshipment problem, location problem, matching problem, assignment problem, packing problem, routing problem, Critical Path Analysis and PERT (Program Evaluation & Review Technique).

Network Analysis

The Windows operating systems have distinct methodologies for designing and implementing networks, and have specific systems to accomplish various networking processes, such as Exchange for email, Sharepoint for shared files and programs, and IIS for delivery of web pages. Microsoft also produces server technologies for networked database use, security and virtualization.