Categories
Information Networking

OpenDNS and Comcast DHCP/DNS issues

Couple of weeks ago, I got knocked off the internet, and it took me awhile to figure out what when wrong.

Background
I’m working with a new client and their application requires a high speed network to do what they want to do. So I finally had an excuse to purchase 1GB network equipment upgrade: a Network switch and a Network NIC.

I installed the switch and NIC without issue, and proceeded to “clean out” my Server.

I literally pulled all cables and took the machine out to the garage and used an air compressor to dust the beast out.

After the major dusting, in which clouds of dust escaped from the open garage, I also removed several unused PCI cards, and finally put things back together, and got the internal network running, but could not connect to the internet.

Issues
I could connect to all my internal machines, but I could not connect from any machine out via Name.

Oddly, I could “ping” outside servers by IP address, but could not by Name, even when directly connected to the cable modem.

A couple of times, after hard resetting the cable modem and firewall/router, there would be access for a while, or be deathly slow.

Resolution
I had to shut down shutdown the network, except for the main server.

Opened DNS manager and cleared any and all DNS caches, along with stopping and starting the server, and a reboot or two for good measure.

Then directly connected the main server to the “cable modem” via wired ethernet.

I changed the Server’s static IP address to be on the same sub-net as the cable modem (192.168.100.1).

Connect to OpenDNS, and delete the old IP information, and setup new IP information.

Reconfig the server back to it’s original IP range, connect firewall/router to modem, and reconnect to OpenDNS.

Finds

I went through all my settings, machine by machine, flushed caches, renewed IP, reset WinSock, etc.

  • Comcast has 1 hour DHCP address renewal
    • Seems that when I had my server down for cleaning, it missed a DHCP “conversation” and my external IP changed.
  • OpenDNS
    • Was using my Old IP address and for some reason would not resolve IPs to Name.

Lessons Learned
Since I originally ran into this issue, it has happen one more time, but I immediately connected the server to the cable modem, reestablished OpenDNS connectivity, and moved ethernet cables back. (Estimated time: 10 minutes vs. Hours of Troubleshooting)

I have also downloaded and installed the OpenDNS agent, and is running all the time.

– Andrew
§ § § § §
[adrotate banner=”1″]
Categories
Information Reference

OpenDNS and GoogleDNS

This is a rehash of a Facebook conversation from earlier today….

Originally, I posted a link to “Google Public DNS offers speed, few features” in which I made the comments that this could get interesting, and ended up doing a quick DNS description:

“DNS is a foundation level services that helps run the internet. Every device on the internet has a unique IP number that usually takes the form of [74.125.53.100]. Since humans are not that good with remembering numbers, we add names, such as google.com… What DNS does is translate backwards and forwards of IP Numbers [74.125.53.100] to Human Name [google.com]. Think of DNS as a Yellow & White pages phonebook for the internet.”

“When one connects to the internet from home or at work, that device uses DNS to find “stuff” for you. If you have an ISP (Comcast, Verizon, etc.) they give you their DNS Server addresses, which is fine for most folks, but with a little bit of techo-tink, one can access Open Public DNS servers that are usually faster then an ISPs, so your access is a bit faster.”

“Setting up your account is primary, but once done, the basics are that you need to access your router/firewall and change the DNS servers that they are “pointed to”. Some routers offer away to add more the two (2) entries. If this is possible, make your Open Public DNS servers the Top priority in the list.”

As a reference:

OpenDNS
208.67.222.222
208.67.220.220

Google Public DNS
8.8.8.8
8.8.4.4

– Andrew
§ § § § §
[adrotate banner=”1″]
Categories
Software

Dynamic IP on NIC during AD/DNS Setup Issue

When setting up a Active Directory domain, dcpromo.exe can include the required DNS installation, but the Wizard may warn you that you have one NIC adapter that is NOT set to static.

This is generally caused because both IP4 and IP6 are installed by Default and both need to be set I found a quick and dirty on-line/web based utility that can help you convert the IP4 to IP6 address:

<http://ip-lookup.net/conversion.php>

An alternative approach is to just Disable IP6 for the NIC, since to take advantage of IP6, the rest of your networking infrastructure also has to support IP6 (Gateways, Routers and Switches).

Hope this helps!

– Andrew
§ § § § §
[adrotate banner=”1″]