DHCP - Pre-populate Hostname for Reservation from DHCP Request, DHCP Logging

[Kurt Schumacher]

Most DHCP clients send their configured hostname with the request. Why is this hostname not pre-populated as a name towards the address reservation?

Why are there no system log enties of the DHCP operations - requests, ack, ...?

Are my expectations set to high for a Cisco Small Business Router?!?

[ddiep]

Kurt,

We certainly could improve the log to provide more logging info for dhcp request/response. There's dhcp table that contained all dhcp client info included its host name and ip address. I'm not sure if this is you are refering to "pre-populating hostname"?

Thanks.

[Kurt Schumacher]

When a DHCP client is nicely supplying a hostname with the DHCP request, this name should be used to pre-load the form when adding a static DHCP IP entry from the "Show unknown MAC addresses" in the [host]name field.

Inconsistent and misleading is the title of the "Show unknown MAC addresses" pop-up window, named "IP & MAC binding List". Word casing requires revision - but why not using the "unknown MAC addresses" in the title? Misleading is the "IP & MAC Binding List" becaue of binding is commonly used to bind a MAC address to an IP address, and prohibit access to the network when i.e. a user is trying to circumnavigate Cisco ProtectLink where the access control is IP based...

[ddiep]

Kurt,

Now I understand what you're asking.

- Unfortunately the name field is limited to 12 characters and thus can't accommodate to pre-populate w/ hostname that has longer string than that. Though I'm not sure why the limitation, perhaps to save space and how many (maximum) characters  should/can it support is another question.

- Agree that "Show unknown..." and "IP+MAC binding..." are quite confusing. Will ask design/engineering team to change the name to be more consistence.

Regards.

[Kurt Schumacher]

It's strange anyway, the "DHCP name" limit is 10 characters, but the DNS one is at 32 characters.While the static DHCP table is limited to 50 entries, we can't find any infromation about the limit on internal DNS names. The actual combination is adding up to 10 characters plus 12 bytes for the MAC address storage for hosts in static DHCP and in DNS for the 50 entries, while the local DNS should be able to serve [1..n] times 255 hosts, one for the LAN defaulr subnet, and more for all secondary subnets. If configuration and runtime storage is an issue, these two must be combined anyway.

Then the local DNS should be able to resolve both A (name->IP) and PTR (IP->name) requests.

What is the effective limitation for the local DNS please?

This makes it pretty clear, the 10 characters limitation is slightly strange - and the storage place could be streamlined.

Ref. wording - in fact the IP+MAC binding is already in the local DNS settings, see "Block MAC address on the list with wrong IP address" and "Block MAC address not on the list" options.