Router DNS/DHCP Question

Would a router cause one's IP address to become static?

 

If you set your router to dynamic, it will get your IP from your provider. It's up to your ISP if your address changes. I have mine set to dynamic but it hasn't changed, but not because of the router.

 

In order to get a static IP, you would have to enter it manually. Otherwise it's assigned by your ISP. It may not change frequently, but has the ability to do so.

...screamer

 

Greetings screamer......i thought it DID change frequently.....? I have had the same one for the past two days

 

Dynamic IP addresses are normally in my experience leased for a number of days, 72 hours springs to mind. You can, again in my experience force a change of IP address by swithing off your router and thus disengaging from you ISP for a few minutes.

To gain a static IP address, ie one that is always the same would have to be by arrangement with you provider I believe.

 

Its my understanding that if set to dynamic and you are on a LAN,you get your IP address from the inbuild DHCP server in your Router/Gateway and not from the ISP provider,ISP is only concerned with the external IP address[who faces the Web],but then again i maybe wrong about that!!

 

Not that it may matter but who is your ISP if you don't me asking.

With Road Runner and now Comcast....it was\is not unusual to keep the same IP for numerous days.

Bubba

 

Its all dependant on your ISP, most charge extra for static address, otherwise they all keep it dynamic, reboot the router and you will see your IP change.

 

He's referring to the IP address from his ISP

 

The routers DHCP Server assigns Dynamic "LAN" IPs or Static "LAN" IPs if you direct it to do so. My LAN has 3 Dynamic IPs for the computers and 2 Static IPs, 1 for NASbox & 1 for Wii. Dynamic DHCP clients (LAN) expire after a set amount of time, or can be re-set manually. Obviously Static IPs remain intact. ISP DHCP assigned IPs also expire or can be re-set. Either by re-booting your modem / router or by a re-set switch on some routers. My ISP assigned IP has been the same for many days now. You can request a Static IP from your ISP for a nominal fee ~$10.00

...screamer

 

Hello,

My ISP has two ways of handling customers:
Dynamic IP for people connecting with VPN dialer
Static IP for people always connected (as soon as the OS resolves the address)

In the case of the first, the address can change several times during a session, depending on its length and whatever server requirements on the server side. But it can also remain the same for up to 2-3 weeks (I've seen this).

In the case of the second, the address never changes.

My experience.

Regards,
Mrk

 

I have disconnected both modem and router for up to 15 mins, yet when reconnected the address is the same..... This is new behavior...... Also, the node type on my ip configuration is Hybrid. I had thought this was for Lan usage. I am on a stand alone computer.

 

Ok...i need some help trying understand what is going on here.....i installed the Castle IPAddress program and it is showing a different address then their visible address finder ( http://www.castlesoftware.biz/ip.htm ) is showing. When i go into safe mode the IPAddress (small downloaded program from same people)shows yet a third address. The address shown in safe mode seems to be right, from my memory of the expected range. I did a malware scan and found nothing of importance
This might be related or not: I just noticed, after doing an ipconfig /all, that Net Bios over Tcp/Ip is enabled..........i have long since disabled Net Bios over Tcp?IP in services. Am i right in thinking something is rotting in Denmark?

 

How do i do this ?

 

Hi Rainwalker,

As mentioned, it would depend on the router settings. Most, by default will obtain a dynamic IP (given via DHCP by your ISP.

Some ISP`s (cable etc) will issue an IP, then bind this with the MAC address of your hardware. I have been with my ISP for about 2.5 years, the only time my IP changes, is if I change hardware MAC address.

Being behind a router, your PC IP will have a private IP,.. possibly 192.168.*.*, your external IP will be in the router.
So an internal scan of IP, will show different to external scan of IP (with a router)

 

Thanks Stem.......this broadband is new to me........yes, 192.168.*.* and if the external IP is different, yet not changing much, does this not pose the same security risk as a static address...........and why was i seeing that third addy in safe mode? Again, the 3rd address is the one that will change frequently.

 

Hi Rainwalker,

I dont normally see problems with direct (sustained) attacks against an home PC IP.
If you feel uneasy with such an IP, and at some point want to change, then go into the router,.. most will allow the changing of the MAC address, note down the MAC address, then change the last 3 digits,.. then reboot the modem and the router. This will show if your ISP will allow such a change (some will not~ so you may have to change the MAC address back to original), but normally, the IP will change due to the different MAC address.

Did you start "safe mode" with networking enabled?
If the IP is not resolved (no DHCP or networking), it will normally default to an address such as 169.*.*.*

 

OK......yes, safe mode w/networking.

 

Your PC should still then resolve IP,.. but the IP could change, but should still be within the LAN range.

As with my one of my LANs,.. this is 192.168.1.1<->192.168.1.255,.. the PC, with DHCP, could (on boot) be given any IP within that range. (normally, the router is 192.168.1.1, and 192.168.1.255 is for broadcast), so (in such a setup) the PC could be any IP from 192.168.1.2 to 192.168.1.244

 

Ok...those numbers are as they should be here..........would it matter that i am on a stand alone computer?

 

Your PC will still be seen (as from the router) as part of a LAN. It will issue (via DHCP) the IP for your PC IP. It could stay the same, or change, it would depend on how the internal DHCP server of the router works ~mainly on the lease given/stored, (the lease, is basically the time given for an IP before a need to check/renew)

Being on a single PC behind the router, then internal DHCP/ARP should never be a problem to you. Only if you where to use a P2P client, then the changing of your IP can cause problems to the settings made in such software,.. then it may be better to fix your PC IP.

 

OK........i will keep an eye on the lease expiration and report back after the expiration. This has been very helpful Stem. Thank you.

 

If the lease expires while the PC is on, then the IP will simple renew (stay the same). Only, if for example, the lease expires (within the router) while the PC is off will your internal IP (possibly) change.

You should not worry about this on your own home LAN, is it just how LAN works, and can simply be left alone (in your setup).

Only, as I put forward, would a need to change this is if you use P2P,.. then we would set your internal IP as static, and port forward from the router.

 

No big deal to change to static or back to dynamic, you don't need to pay for one: http://www.portforward.com/networking/staticip.htm

 

How safe is this