Internet connection very slow after clients join domain


I have one windows server 2012 when clients are join to the domain internet connection will be very slow I have no idea what is problem because I am beginner,
clients are using wireless to access internet not using wire.

Best Answer

From what you say I do believe your error is DNS related.

Just to quickly understand if I am right please temporarily delete any dns entry * from a single testing **client *** and add as a primary dns server (Google's DNS).

From a command prompt use:

ipconfig /flushdns

And test your navigation again.

If now it works fine it probably means that you need to check your DNS forwarders on the server.

If my idea is right and your test confirms it, here I past relevant information to configure your DNS forwarders (source

To configure a DNS server to use forwarders using the Windows interface Open DNS Manager. In the console tree, click the applicable DNS server. Where? DNS/Applicable DNS server

On the Action menu, click Properties. On the Forwarders tab, under DNS domain, click a domain name. Under Selected domain's forwarder IP address list, type the IP address of a forwarder, and then click Add. Additional considerations To open DNS Manager, click Start, point to Administrative Tools, and then click DNS.

To create a new domain name, click New, and then, under DNS domain, type the domain name.

When you specify a conditional forwarder, select a DNS domain name before you enter an IP address.

By default, the DNS server waits five seconds for a response from one forwarder IP address before it tries another forwarder IP address. In Number of seconds before forward queries time out, you can change the number of seconds that the DNS server waits. When the server has exhausted all forwarders, it attempts standard recursion.

If you want the DNS server to only use forwarders and not attempt any further recursion if the forwarders fail, select the Do not use recursion for this domain check box.

You can disable recursion for the DNS server so that it will not perform recursion on any query. If you disable recursion on the DNS server, you will not be able to use forwarders on the same server.

Do not enter a forwarder's IP address more than once in a DNS server's forwarders list because it is a more reliable or geographically closer server. If you prefer one of the forwarders, put that forwarder first in the series of forwarder IP addresses.

You cannot use a domain name in a conditional forwarder if the DNS server hosts a primary zone, secondary zone, or stub zone for that domain name. For example, if a DNS server is authoritative for the domain name (that is, it hosts the primary zone for that domain name), you cannot configure that DNS server with a conditional forwarder for

You can prevent common problems that are associated with forwarders by configuring your DNS servers to avoid overusing your forwarders.

If you prefer a much more visual guide I think that this one available on OpenDNS is well done (I am sorry for just putting the link but there are a lot of images and the copy and paste becomes meaningless without them):

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