[c-nsp] DNS forwarding/proxy

[Brant I. Stevens]

How about using NAT for port-redirection to send the requests to the "real"
DNS server?


On 7/18/06 7:12 AM, "Florian Prester" <Florian.Prester at rrze.uni-erlangen.de>
wrote:

> Oliver Boehmer (oboehmer) wrote:
>> Check out "Split DNS" feature (very new, 12.4(9)T,
>> http://www.cisco.com/en/US/products/ps6441/products_feature_guide09186a0
>> 0806bd780.html), which could do what you need, but likely not on your
>> platform :-|
>> 
>> What are yoy trying to achieve?
>>   
> We are restructuring a network, containing about 500 Clients which are
> used to take the default gateway as DNS-Server too.
> But within the new network there is a different DNS-Server, which IP is
> unequal to the default GW.
> 
> So now I want to redirect the DNS-Traffic so I, or the others do not
> have to alter all the DNS-Server-Entries on the Clients, unfortunately
> they do not use dhcp, yet.
> 
> Florian
> 
>> oli
>> 
>> Florian Prester <mailto:Florian.Prester at rrze.uni-erlangen.de> wrote on
>> Tuesday, July 18, 2006 12:19 PM:
>> 
>>   
>>> Thanks for your answer, even if it does not sound very good :-(.
>>> 
>>> Is it possible to redirect some traffic by using ACLs?
>>> I think I have read something about doing so, but cannot remember
>>> where and on what system.
>>> 
>>> Thank you
>>> Florian Prester
>>> 
>>> 
>>> Oliver Boehmer (oboehmer) wrote:
>>>     
>>>> There is "ip dns server" (don't think it is available on the Cat4500
>>>> software releases, but it is in 12.2T/12.3 and later releases in some
>>>> advanced feature sets) which turns a Cisco router into a caching DNS
>>>> server, it uses the configured "ip name-sever ...." addresses as
>>>> forwarders. There is little documentation for this feature (we're
>>>> working on it), but next to the "ip dns server", there are also new
>>>> keywords for the "ip host ..." command..
>>>> 
>>>> oli
>>>> 
>>>> Rodney Dunn (rodunn) <> wrote on Thursday, June 29, 2006 4:06 PM:
>>>> 
>>>> 
>>>>       
>>>>> My bad..not enough coffee yet in the morning.
>>>>> 
>>>>> I thought you meant dhcp.
>>>>> 
>>>>> I don't know the answer.
>>>>> 
>>>>> On Thu, Jun 29, 2006 at 04:00:08PM +0200, Florian Prester wrote:
>>>>> 
>>>>>         
>>>>>> Rodney Dunn wrote:
>>>>>> 
>>>>>>           
>>>>>>> Did you try configuring an "ip helper address x.x.x.x"?
>>>>>>> 
>>>>>>> 
>>>>>>>            
>>>>>> I think an ip helper address is only for Broadcast traffic?? Is it
>>>>>> not? I want the router to accept unicast dns requests to its own IP
>>>>>> and act as an DNS-Server by asking another DNS-Server (or proxying
>>>>>> the request to the other sever).
>>>>>> 
>>>>>> Greetings
>>>>>>  Florian
>>>>>> 
>>>>>>           
>>>>>>> On Thu, Jun 29, 2006 at 03:11:05PM +0200, Florian Prester wrote:
>>>>>>> 
>>>>>>> 
>>>>>>>            
>>>>>>>> Hi,
>>>>>>>> 
>>>>>>>>  is it possible to configure a Catalyst 4500 (SupIV) to act as a
>>>>>>>> DNS Proxy? Or at least to tell it to forward incomming
>>>>>>>> dns-requests to a specific DNS-Server?
>>>>>>>> 
>>>>>>>> 
>>>>>>>> Thanks
>>>>>>>>   Florian
>>>>>>>> 
>>>>>>>> 
>>>>>>>>           
>>> --
>>> Dipl. Inf. Florian Prester
>>> Network Administration
>>> Regionales RechenZentrum Erlangen
>>> Universitaet Erlangen-Nuernberg
>>> Martensstr. 1
>>> 91052 Erlangen
>>> Germany
>>> 
>>> Tel.: +499131 8527813
>>>     
>