how to find out if secondary ip address of vlan interface is used

[hmc250000]

We have a vlan interface configured with multiple secondary ip addresses on one of our core L3 switches. Now we do not know who or why those secondary ip addresses were configured. How can we find out if the secondary ip address of a vlan interface are still being used? 

[marce1000]

 - It's a  bit off topic for good network management but anyway ; You need to monitor traffic on the switch and check if there's any destinations with that IP address , by for instance configuring   a span port for the vlan , other methodologies could be applicable. 

 M.

[Flavio Miranda]

@hmc250000 

 Check the routing table

Check the ARP table

Creare ACL with secondary IP address and check hit counts.

[Richard Burts]

I wonder about the suggestion to check routing table and arp table, since they both reflect remote devices that access this device but do not indicate which address on the local device is accessed. But I very much like the suggestion to use an ACL. If the interface has an existing ACL for inbound traffic edit the ACL and insert as the first entry a permit ip any <secondary_address> and if the interface does not have an existing ACL the create and apply an ACL with the first entry being permit ip any <secondary_address> and the next entry being permit ip any any.