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DNS issues

Posted on 2013-05-21
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Last Modified: 2013-05-21
Last week our ISP forced us to change our public IP Addresses. Everything "seems" to be working fine, except for the fact that we are not certain emails and our internet does not work internally now unless I add the DNS of the ISP to each pc/laptop. We use Active Directory with an internal Exchange 2010 server. THe network settings for each pc were pointed to (2) internal DNS servers (do not have a public IP Address associated). Before the change our internet worked great and we were receiving all emails, but not now. The ISP claims they have no issue with what is going on, but aside from the public IP change, nothing else has changed. Please help???
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Question by:fallriverelectric
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by:BillBondo
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How are your servers set up for dns? They should only point to themselves. Sounds like they may have an incorrect setting.
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by:Rsilva98
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hi

If your ip changed it will take some time until all propagate correctly.

How come you dont have public dns ? Is your internet ip static or dynamic ?

Since you have exchange you really should consider have public dns otherwise you risk ending on the spaming  lists. also you get blacklisted on most email server,
You are able to receive emails but you cant send it.

If you have a dynamic ip you can do two things:

 - You need to send out emails through your ISPs mail relay. If they don't offer such a service you can still try to find a commercial SMTP relay elsewhere on the internet.
- Your ISP must not block SMTP (TCP port 25) connections to your IP address. If they do you cannot be sent emails from other mail.
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by:fallriverelectric
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MY internal DNS's only point at themselves.

I realize it will take time to change, we made the change on Friday afternoon and we started seeing traffic to the new IP's within an hour.

Our internet comes from our Cisco router. We have public static IP's on the router. We do not host our own website, and our Exchange email server has a public IP NAT on the router to the internal address of the mail server.
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by:rauenpc
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Do you have DNS forwarders configured on the servers, or are you just using DNS root servers?
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by:m3mph1s1
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Have you purged the DNS cache on the workstations and the server?
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by:fallriverelectric
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Where do I configure the forwarders? DO I do that, or should my ISP do that?

I have purged the DNS cache on workstations, servers and routers.
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by:m3mph1s1
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You configure the forwarders in the DNS console under forwarders
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by:blongacre
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What version of Server are you running?

Server 2003

Click Start
Click Control Panel
Click Administrative Tools
Click DNS

Right Click on your server name in the tree on the left hand side of the DNS console
Click Properties
Select the Forwarders Tab
Select All other DNS domains
near the bottom, enter the New IP addresses, then click Add
Select the old IP addresses, then click Remove

Click OK

Then on your server and your computers run ipconfig/flushdns from the command prompt.(with Vista, 7, or 2008, this will require elevation of cmd)
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blongacre earned 500 total points
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For Server 2008

Everything is the same until you have selected the Forwarders Tab - then

Click Edit
Add the designated IP addresses then press Enter
Select the old, obsolete IP addresses
Click Delete
Click OK

Then again follow the same directions to run ipconfig/flushdns
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by:fallriverelectric
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I believe the forwarders issue has fixed my internet problem, I forgot about that, not sure why. However, will that take time to fix my email issue?
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