Huge, in response to your question, every network is setup different. The minimum you will usually need (from your ISP, either cable or DSL) is an IP address, subnet mask, default gateway and DNS server....but that's only if everything is static. Many ISP's (like mine, I have a cable modem from Insightbb in Bloomington, Indiana) go straight DHCP...they force all the addresses onto every device connected to the cable modem network (usually your home router, sometimes your home PC or PC's).
I know some DSL providers give you the option of getting either a static IP or a dynamic IP, the difference being that the static IP is public, where the dynamic IP is private to the DSL network. The private IP is harder to hack since it is behind a NAT firewall, but you cannot use VPN without a public IP.
My cable modem IP is dynamic (but I do get the same IP every time because Insightbb reserves IPs based on MAC addresses) yet public, which in my opinion is the best of both worlds since I don't have to remember all the IP addresses everytime the power goes out, yet I can still VPN into work or IU.