Security

ip dhcp snooping

Enable DHCP snooping globally; add 'ip dhcp snooping vlan <id>' per VLAN and 'ip dhcp snooping trust' on the uplink toward the real server.

Works on: SwitchMode: config

Watch out

Configuration-only in this lab: 'show ip dhcp snooping' reports the state, but snooping never drops a DHCP message here, so a second DHCP server on an untrusted port still hands out leases.

Run this command live

Don't just read it — type ip dhcp snooping in a real network simulator in your browser and watch it take effect. No install, no account needed to start.

Open the lab

Frequently asked

What does the "ip dhcp snooping" command do?

Enable DHCP snooping globally; add 'ip dhcp snooping vlan <id>' per VLAN and 'ip dhcp snooping trust' on the uplink toward the real server.

What's the common gotcha with "ip dhcp snooping"?

Configuration-only in this lab: 'show ip dhcp snooping' reports the state, but snooping never drops a DHCP message here, so a second DHCP server on an untrusted port still hands out leases.

More Security commands

access-list <10-99> {permit|deny} <src> <wild>ip access-list extended <name>ip access-group <acl> in|out switchport port-security switchport port-security maximum <n>switchport port-security violation {shutdown|restrict|protect}switchport port-security mac-address {<H.H.H>|sticky}ip arp inspection vlan <id>line vty 0 4 line console 0 password <password>login

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