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Thread: DNS Query

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    DNS Query

    I have a query and I am not sure if it can be done, but is it possible to enter the IP addresses of gateways in DNS Server, so that clients do not have to specify a gateway address to access the internet? I do not know much about DNS and have inherited it off someone - but is this possible? The problem I am having is that without a gateway address specific, clients are unable to access the internet. I have entered the address of our 2 gateways in MS DNS but it does not seem to work. If this can be done, then I would be grateful for some idiot proof instructions. If not, then it would be nice to know why so that I can explain it to my bosses.
    Thanks alot

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    Re: DNS Query

    Hi,
    If I understand you correctly then the answer is no. An entry in a DNS server simply allows the server to translate a host name into an IP address. If the client machine doesn't have a gateway specified, then it will query the DNS server to get the external address of whatever site it's trying to access but will then simply try to send via whatever route is in its local routing table. If you're using DHCP on your network rather than static addressing, then your DHCP server can automatically assign various configuration items to each network client - DNS/Wins server addresses, gateway addresses etc.
    Does that help?
    Regards,
    Rory

    Microsoft MVP - Excel

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    Re: DNS Query

    Thanks, I did not think it could be done. I did however, speak to friend of mine who suggested this alternative: -
    1. Set up the DNS Servers to have an external gateway to a DNS server on the web.
    2. Set up forwarding on the DNS servers to the external DNS Servers.
    I am not sure if the above would work. He seems to think that with the above, client machines would not require the address of the gateway on their local machines.
    He did however warn me that doing the above would slow down connections to the internet considerably as it the DNS Server would try to resolve the addresses first before forwarding it to the external DNS server.
    Is he making sense?

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    Re: DNS Query

    I think he's talking about something different from what I'm talking about! His solution simply allows your DNS servers to resolve hostname to IP address requests for internet sites. I had assumed you already had the DNS bit sorted out - i.e. the client machines knew which address they were trying to reach, they just didn't know how to get there?
    Basically there are two stages for the client:
    1. User types in www.whatever.com and client issues a request to each of the DNS servers it kjnows about until it receives the IP address for www.whatever.com (or a failure message)
    2. Having got the address, the client then needs to know via what route to contact that address.
    I assumed it was part 2 you were having trouble with, in which case your friend's suggestion won't help.
    If you open a command prompt on a client machine and type 'route print' (without the quotes) you will see a dump of the routing table, listing network addresses, subnet masks, gateways etc. The first entry starts 0.0.0.0 which is basically the catch-all for any address not covered by the other entries (this usually cover internet addresses). The gateway address for this item is the address that the client will send all transmissions to for forwarding to the outside world.
    What I would like to know is why you can't add a gateway address to each machine?
    Regards,
    Rory

    Microsoft MVP - Excel

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    Re: DNS Query

    Thanks alot for this, believe me, I would dearly love to have all the machines have a gateway address. The problem I am having is someone a long time ago set it up for my client and it was removed, and now they want it back!!! Apparently the reason why it was removed, was because of speed issues but now I want it back. Essentially, the issue they have is this: -

    1. We set up an intranet for them using 2 IIS Servers and a SQL Server (for the database).
    2. Using round robin DNS, they are able to log onto the intranet which works fine.
    3. Within the site, they have set up internet connections to other sites.

    The issue they have raised is that when 'we' first set it up for them, they could use round robin DNS and connect to internet sites and they did not have to add a gateway address on their client machines. This was set up by a former member of staff who left the company. I am not sure that it was set up but the client swears blind that it was. Now they want their non-essential support staff to be able to connect to the internet via their intranet but without specifying a gateway. For those essential staff however, where speed is the issue, they want to be able to specify a gateway.
    I managed to speak to the person who originally set it up who suggested the option I mentioned although I was not convinced that it worked. This is a classic scenario of a client who wants something done because they seem to think that it can be done or they claim that it can be done. I do not have much knowledge of DNS hence my posting. Is this possible? Is so, can you please tell me how to do it? I really need idiot proof instructions on this one. Essentially, what they want is this: -

    1. For some clients to have gateways specified locally on the client machines.
    2. For other clients not to have the gateway specified on the client machines but for the DNS Servers to route their internet connections to their gateways.

    Thanks
    Kutty

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    Re: DNS Query

    The only ways I know of that don't involve specifying a default gateway (as such) are configuring the local routing table or going through a proxy server - you need to set that up in the connections tab of Internet Explorer. I don't know enough about intranets (I know almost nothing in fact!) to say whether you can set up a link on an intranet page and include routing information within it.
    DNS servers are not routers (though a server running DNS may also be functioning as a router) and so I fail to see how anything set up there could possibly affect a client's internet connection. The only transmission the client will make to a DNS server is to resolve the hostname into an IP address - it does not attempt to contact that address via the DNS server.
    I believe it is possibly for the local routing table to be automatically configured if you use routers that meet certain specifications.
    Hope that helps?
    Regards,
    Rory

    Microsoft MVP - Excel

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    Re: DNS Query

    Thanks for your help. If I come across anything else, I will let you know. Sometimes I wish clients would simply leave things as they are. If it ain't broke.....

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