ISP dynamic IP address service

[npranger]

Hello,  I am configuring a router with port G0/0 connected to the ISP modem.  In taking examples off the internet I have inserted a single IP (12.34.56.2) address that is currently comes into the customer's building.  What happens when/if the ip address changes from the ISP?  How should I list the IP address on the global outbound?  I hope you understand what I am trying to say.

Thanks, Phil

[balaji.bandi]

if the single IP (12.34.56.2) is RFC 1918 address, the ISP Modem automatically takes care of NAT.

If this is a real IP address you need to contact ISP, is this IP DHCP or an allocated static IP address for you?

based on the answer from ISP you need to change (if ISP looking to change) - if this is setup to DHCP then you need to worry that automatically get new IP address

Note: this depends on the ISP offers.