tell static ip address from all address

[wfqk]

Hi in switch4500, "show ip arp" can show mac and ip address, which are user PC's ip address. Do we have a command which tells which is static ip address or dynamic ip address? Thanks

[swicklund]

I don't know of any way to tell that from the switch.  Usually you just do that on the dhcp server.  

[wfqk]

thanks for your reply. if we assign an ip address, for example, 10.1.1.10 as static ip address for first PC, but this ip address is just about to be assigned to second PC by dhcp, what would happen? it would produce duplicate ip address 10.1.1.10, one is static ip and other is dynamic ip, or just produce a dynamic ip address 10.1.1.11 to the second PC? we do not exclude 10.1.1.10 in dhcp server.

[swicklund]

Regardless of if you are running DHCP off a server or a Cisco device you would typically define the addresses you want to be assigned by the server/device.  Other address you would assign manually.  That way the DHCP server could not assign an address that you would set manually.  In other words you would tell the server use addresses 10.0.1.1-10.0.1.10 and then other address you would set manually.  

[acampbell]

Hi,

Most DHCP servers Including the Cisco IOS type should perform a ping before giving out a lease of an IP address.
It the address responds due to say some one has blagged it for a static the DHCP server should mark this as a bad address in its lease table.

https://www.cisco.com/en/US/docs/ios/12_4t/ip_addr/configuration/guide/htdhcpsv.html#wp1027188

Ping Packet Settings

By default, the DHCP server pings a pool address twice before assigning a particular address to a requesting client. If the ping is unanswered, the DHCP server assumes (with a high probability) that the address is not in use and assigns the address to the requesting client.

By default, the DHCP server waits 2 seconds before timing out a ping packet.

  1. enable

  2. configure terminal

  3. ip dhcp ping packets number

  4. ip dhcp ping timeout milliseconds

Here is an old MS link for a 2003 server to do conflict prevention
https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2003/cc737924(v=ws.10)