I have a switch configured to resolve hostnames, it works fine, if I ping local or whatever it looks up the IP and displays output. So If I find an IP address in the arp table and want to resolve its hostname, is there a command like Windows nslookup that will allow for this?
There is nothing built-in, but attached is a Tcl script I wrote to do A and PTR DNS lookups using the IOS tclsh (in IOS 12.3(2)T or later, 12.2(18)SXF5 or higher, 12.2(40)SE or higher, etc.).
As a final step, we set the FQDN we'll be updating and enable the DDNS service on our public interface (usually your Dialer 0 or public Ethernet interface): This completes the setup and your router should start sending its updates to the DDNS provider.
If you see that the your FQDN hasn't been updated after 5-10 minutes, then you can also use the following debug commands (hit CTRL-Z first) to get an idea on what's happening in the background: Jan 24 .859: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access3, changed state to down Jan 24 .859: DYNUPD: SWIF goingdown 'Virtual-Access3'Jan 24 .091: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access3, changed state to up Jan 24 .091: DYNUPD: SWIF comingup 'Virtual-Access3'Jan 24 .883: DYNDNSUPD: Adding DNS mapping for firewall.In this article we've covered how to enable and configure Dynamic DNS for popular and
This eliminates the need for a static IP address, since the DDNS provider will automatically update its DNS records with your dynamic IP address every time it changes.
From Cisco IOS version 12.4 onwards, Cisco routers have built-in support for a variety of DDNS providers, making it much easier and a more reliable alternative, as you no longer require a PC in your network that will run the DDNS provider's client program.
Once received, the DDNS provider updates the relevant DNS records, in our example, firewallcx.