Internet connection on core router in a non routable vlan

[HamDawg]

hello techs, i am curious...

is it safe to plug an internet connection in to a core router within a none-routable vlan?  is there are security risk where this vlan isn't advertised to no internal network- but with just the devices within?

i have a vlan 100 where is have a DSL internet  connected on g1/0/1 through g1/0/5

switch mode access

switchport access vlan 100

is there any harm in doing this?  devices plugged in to this vlan get IP from the DSL device in g1/0/1

would there be any other paramter i can assign to these switchport to make it more secure?

thanks in advance,

[W-ALI]

for more secure,to any unused interface

shutdown or configure port-security , or 802.1X , or assign it to any internal VLAN

[MHM Cisco World]

if the SW server many LAN and you under attack of DDoS, then the CPU will be high utilize and all your network Down.
that why we need ASA FW or Router with Zone based Firewall connect to Internet.

[HamDawg]

thanks for your inputs all.  appreciate this.