[X4U] IP address on local network

[Neil Laubenthal]

Sure . . . here's a brief description of the difference.

You get a single public IP fro your ISP and it is assigned to your  
router. The router does something called Network Address Translation  
(NAT) to allow multiple computers at your house to simultaneously  
access the internet.

Each computer inside your house needs an IP address  
obviously . . .they're usually assigned in the 192.168.x.x or  
10.0.x.x. ranges as these IPs are not directly routable on the internet.

If you use DHCP (Dynamic Host Configuration Protocol) then your router  
hands out IPs in a specified range, along with the router's address  
and DNS server addresses as supplied by your ISP. These IPs have a  
lease time until they expire so that they can be reused. They can be  
assigned completely dynamically which means one particular computer  
may have a different IP today than it did yesterday. This is fine if  
all you want to do is get to the internet . . .but if you want to  
connect from say your laptop to your desktop then you need to know the  
desktop IP.

If you assign a static IP to each computer then it stays the same and  
you can easily connect to other computers in your house. However,  
static IPs are a little harder to manage.

One way to get the advantages of both dynamic and static is to use  
DHCP but set address reservations. On your router . . . you enter the  
MAC address (Media Access Control, not the same thing as a Mac) of  
each computer and tell the router to dynamically assign IPs but to  
always assign 192.168.1.5 to mac address xyz . . .that way your  
desktop always has the same IP assigned.

I personally use static IP addresses for all my computers at  
home . . . but keep a DHCP scope setup but inactive as well for when I  
have visitors, that way they don't have to do any fiddling  
around . . .I just enable the scope while they're here and they can  
connect.


On Apr 25, 2009, at 6:28 PM, Daly Jessup wrote:

>> Thanks for the information.  I thought DHCP had some security  
>> advantage.  But, if it's mostly just an easy way to give out IP  
>> addresses, I'll have to try this hybrid method.
>>
>> On Apr 24, 2009, at 8:23 PM, Daly Jessup wrote:
>>
>>> Static IPs allow us to set up access to our home network from  
>>> remote computers, with ports forwarded to local IP addresses that  
>>> will not be changing now and then.  But when a visitor comes to  
>>> our home and tries to connect to our local network, they will be  
>>> able to get an IP address by DHCP without my having to know their  
>>> MAC address.
>
> To tell the truth, I'm not very savvy with these things, and don't  
> understand what the difference would be between having Network Pref  
> Pane use DHCP with manual IP assignment, or having the router  
> reserve IP addresses by MAC address.
>
> Either way, it seems your computer gets a "permanent" internal IP  
> address.
>
> Can some more geeky person explain the difference? (Or is the  
> question so ignorant as to make it unanswerable short of a book?)
>
> Daly
> ----------------------
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