Question About DNS

Discussion in 'other firewalls' started by DX2, Sep 6, 2012.

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  1. DX2

    DX2 Guest

    I have a Comcast Router model - SMCD3GNV. Which you cannot enable a static DNS to it. Am I protected just the same if I have DNS on my computer itself?
     
  2. itman

    itman Registered Member

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    What do you mean by "static DNS?" If you are refering to a static DHCP address, I copied below a post from the Comcast forum about this.

    If you are referring to assigning a fixed address to which DNS servers you want to use e.g. OpenDNS., NortonDNS, etc., you set that up on your PC LAN connections settings. That will override anything set up on the router.

    From Comcast forum:

    Re: Turning off all router settings on a SMCD3GNV.

    Options . . ..

    06-24-201102:23 AM

    If you turn off the DHCP function in the gateway, then yes you will have to manually configure each device that needs an IP address with a unique static IP address. Doesn't sound like what you want to do at all. The gateway SHOULD remember the IP addresses it has issued to systems in the past and give out the same one, but if hte lease on the IP has expired, it may reuse the IP address for something else.

    I do recommend that systems which youa re forwarding ports to have static IP addresses so there is no chance it will change.

    You have several choices.

    1. Modify the router's DHCP IP range so that it leaves some IP's unmanged and then assign these unmanaged IP's statically to the systems that need them. The default DHCP managed range is 10.0.0.2 to 10.0.0.252. leaving you with only .253 and .254 as valid static IP's. I would change the end address to 10.0.0.199, which leaves 10.0.0.200 to 10.0.0.254 for static assignment. This leaves the DHCP function up and working for systems that need it while still giving you some static IP's to assign anyway you see fit.

    2. Use the router's Add Computer with Static IP function. The documentation is sparse here, but it looks like you can exclude an IP from the DHCP server using this, but it also might assign the same IP to this device using DHCP. The exact mechanics of this function are NOT explained so you can try it and see if you like. The doc makes mention of wireless devices so this may only work with wireless connected systems, but hard to say.
     
  3. DX2

    DX2 Guest

    I was saying that you cannot change the DNS in my router from comcast. Here is a quote from a person on the comcast forums...

     
  4. itman

    itman Registered Member

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    That's what I posted previously. Enter the IP addresss of the DNS servers in Primary and Secondary DNS servers area. See my attachment.
     

    Attached Files:

  5. DX2

    DX2 Guest

    Yes, I've did this :)
     
  6. TheWindBringeth

    TheWindBringeth Registered Member

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    Don't forget to do that on every computer that you want to use that specific DNS server.

    I would point out the option of acquiring your own router and putting the Comcast router into bridged mode. Read to the end, hopefully things have improved:

    http://forums.comcast.com/t5/Home-N...all-router-settings-on-a-SMCD3GNV/td-p/957393

    That way you will have *your own router* protecting your network (from Comcast equipment, etc) and some additional flexibility. Just don't by a router with cloud features.
     
  7. itman

    itman Registered Member

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    I went through the Xfinity user manual. Not one reference to the existance of a DNS server within the router itself or info on entering DNS IP server addresses. Appears Comcast has indeed crippled all DNS address changing capablitiy.

    One more reason for not using anything Comcast based for the Internet.

    When I am faced with something like this, I first find out who is the real manufacturer of the router e.g. Motorola, etc. I then download the manufacturers user manual. And finally search the web for ways to hack the device. For routers this usual involves downloading the OEM's firmware and updating your router with it. If it works, you can access all the routers features and options. It it fails and your lucky, nothing changes. If your unlucky, your Comcast router now becomes a door stop and you owe Comcast for the cost of the router.

    What WindBringeth suggested might be your easiest option if you have the $$$ to shell out for a good router.

    Have you tried to do a hard reset on the Xfinity device and the see if it will recognize your LAN entered DNS server IP addresses?
     
    Last edited: Sep 7, 2012
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