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subnetted dns server

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by westonmoore

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I am in a fractionalized T1 smart building. My isp gave me 5 ip addresses 63.209.32.130-135 w/ subnet mask of 255.255.255.192. I am running win2k server on .130 w/ a primary dns server, it recieves the T1 on .130 and it proxies requests through another card w/ RAT (10.0.0.1). The .130 nic has my isp's primary and secondary dns for dns, and my .1 card has my primary and isp. on the same network, i have .131 as a secondary, it recieves the T1 also from the router on .131 and also is connected to network through 10.0.0.2. My clients are set to first look to my primary for a dns server then to my isp's primary. i have registered my primary and secondary w/ networksolutions. my problem is this - my clients are unable to use my primary and default to my isp's dns. when i perform a nslookup from my primary or a client, i am told that "can't find server name for address 63.209.32.130: No response from server" when i then nslookup my domain, i get a non-authoritative reply w/ my primary. I believe the answer lies in creating a subnetted reverse lookup zone, as outlined in http://support.microsoft.com/support/kb/articles/q174/4/19.asp, so that i may be authoritative for my range, 130-135. however, w/ a subnet of .192 im not sure how that translates to .130-.135. also, the article says a subnetted infrastucture does not dictate such a reverse zone, its an administrative choice (although it doesnt appear to working otherwise) the article outlines steps my isp (parent) would have to taketo their reverse zone as well as steps i would have to take a far as i can tell. can someone please tell me what i have to do to get my dns working unde this setup?

5 replies

by wburdine

The subnet .192 allows you five IP addresses which "Pac Bell" gave you. Thats fine. Did you place another IP address and Subnet for your 10.0.0.1 network on your servers NIC? So your Serves NIC should have two IPs and Two Subnet numbers. Also did you go to each machine on the network and use the 10.0.0.1 as the gateway on each? Using 10.0.0.3 for the first machine with a subnet number of 255.255.255.0 as the subnet? So your server's NIC should be
IP 63.209.32.130 Subnet 255.255.255.192 ANDIP 10.0.0.1 Subnet 255.255.255.0
Your workstations should all have the gateway set to 10.0.0.1 and the subnet as 255.255.255.0 While each machine gets a IP of 10.0.0.3-252. Good Luck.

by westonmoore

thats exactly what i did youre correct. my problem though is with the DNS as set forth in the question. what do i need to do to be authoritative for those 5 addresses, wont my isp need to delegate a subnetted reverse lookup zone?

by eastexpert

I must say your ISP uses hmm... an _unusual_ concept of subnetting. Usually ISP's in these cases assign you a real subnet, then they delegate you control over this subnet if they want to allow you your own DNS.

Having done so, they would assign you a *real* standard 63.209.32.128/29 subnet (.128-.135 minus first address for network number minus last address for broadcast address). 1 address would go for the router, e.g. .129, and .130-.134 for your hosts w/real IP addresses - that's still 5IP's for your hosts (+ one for router), totaling six.

They apparently decided to conserve as much IP's as possible, so they assigned your hosts to their bigger /26 subnet for that purpose. Normal subnetting scheme would lose 2 addresses of each 8in /29 subnet. This policy effectively BLOCKS them from delegating the subnet's DNS to you, since you've got NO valid subnet at all.

One only can delegate a real subnet, not just an arbitrary range of (even sequential) hosts. In the "normal" caseit would be 128-135.128.32.209.63.in-addr.arpa. Thus you could have your own primary DNS for the zone.

There's not much you can do about their policy.

I would mail them demanding to add your domain's DNS entries to _their_ DNS zone. This would work.

Really: your network hosts' IP's would resolve properly from the Internet side. You then can set up a secondary DNS server, with zone taken from _their_ DNS server. Then change primary and secondary Nameserver IP's with Network Solutions,primary = ISP's DNS, secondary = YOUR (secondary) DNS. Thus, Internet will see your external names. AND your hosts will see these names. Enable DNS on ALL interfaces of your DNS Server. Host your 10.* zone on YOUR server as primary. It's a non-routable address in the Internet, only your internal hosts will use this zone.

If ISP refuses,... live with it or change ISP.

by westonmoore

your help is greatly appreciated, ive never done this before and having dns issues on a win2k network is killing me. i think ill simply take your advice and have my internal as primary, run a secondary of my isp's, and have them add the dns records for my block, which is on their .192 subnet since i use their .129 gateway - i have addresses 130 - 135. again, thanks.

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