The site in question has a 3620 running IOS 12.1. Its upstream ISP uses DHCP to transfer things like IP address and DNS server address(es), so the router will have its upstream Ethernet interface configured as a DHCP client.
The downstream LAN, connected to the other Ethernet interface, will use static /24 addressing (192.168.1.x) and NAT in the usual manner.
Question: How do we configure the router to forward DNS queries to the ISP's dynamically provided DNS server addresses? We don't necessarily want the router acting as a DNS server, or even a DNS cache. It just needs to transparently forward the queries and return the responses - like a $20 wireless router from Netgear will do.
I found the "dns forwarding" command but it is associated with DNS views which don't appear until IOS 12.4. Besides, this capability must have been around for a lot longer than 12.4. I just can't find how to do it in the IOS docs.
I'm happy to RTFM if someone will point me in the correct direction. Thanks!
Upgrading is no problem, though I notice that the latest version available for the 3620 is 12.3.26 (i.e. no 12.4 versions). Looks like that's barely late enough to get the features you mention.
This leaves one unanswered question: What about the upstream interface running as a DHCP client (ip address dhcp)? I don't necessarily know the DNS IP's and therefore cannot statically include them in "ip name-server w.x.y.z" commands. They come in dynamically when the interface requests a DHCP lease. How do they get configured into the DNS server within IOS?
A third possible option, if the ISP's DNS servers don't change and the 3620 supports it, is to use dynamic addressing and set up your clients to get their DNS parameters along with their IP address from the 3620.
I do believe it's possible to configure the DHCP server in IOS to transfer static DNS addresses, and I'll do that if I can confirm the ISP's DNS server addresses are consistent. But if they're not, I'll still need a way to convey those dynamic addresses to the downstream DHCP clients.
I can't be the first Cisco user to need this ability, so I'm hopeful someone will chime in and provide details.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.