Dynamic IP acting like a Static IP

Forums › Spark New Zealand (including Skinny and BigPipe) › Dynamic IP acting like a Static IP

jaybiz3

3 posts

Wannabe Geek

#154012 15-Oct-2014 12:52

Around March 2013 I noticed the modem's IP address wouldn't change even after resetting it several times, but Telecom said it isn't a Static IP. Last month I called Telecom about the 'Static IP' but they still say it's not a Static IP.

We get a least two power cuts per year and I've resat the modem several time throughout and the 'Dynamic IP' is still the same as it was in March 2013.

How can a Dynamic IP act like a Static IP? (Note: before March whenever the modem resat, the IP did change).

This is a filtered page: currently showing replies marked as answers. Click here to see full discussion.

sbiddle

30853 posts

Uber Geek

Retired Mod

Trusted

Biddle Corp

Lifetime subscriber

#1154399 15-Oct-2014 13:04

It's called a sticky DHCP lease, and yes it works this way on a number of ISPs

BlakJak

1275 posts

Uber Geek

Trusted

#1154410 15-Oct-2014 13:22

Technically it's not necessarily 'DHCP' but the fundamentals are the same.

The network remembers where the IP was, and to what MAC address (or equivalent) it was allocated, and will hold it in limbo for a period of time in order to re-allocate it. This means less network topology changes need to be made/propogated. OTOH if the IP is not in use and the pool is depleted, addresses 'in limbo' will be issued - likely in an order that pertains to how recently they were released. It's efficient.

If someone else is dynamically allocated the IP then you'll get a different one. If that hasn't happened, then you're very likely to get the same one each time.

No signature to see here, move along...

cbrpilot

955 posts

Ultimate Geek

Trusted

Spark NZ

#1155668 15-Oct-2014 20:38

jaybiz3: K, thanks, I guess the question is why would they change it from Dynamic IP to 'sticky/MAC assigned/pseudo-static' IP.

Around the same time (Mar-2013) Telecom did maintenance on TIVO, and my first post on these forums was assuming this had changed it to a 'Static-IP', could it be this?

We would have migrated you off our old network which used very dynamic IP, to our newer network that has stickier IP (to use the term others have used).

All this will be changing though. We're currently rolling through changes that will get rid of those sticky IP addresses for true dynamic again. We introduced the sticky IP addresses back in 2010 when we rolled out a new network for a product that we decided not to launch.

My views are my own, and may not necessarily represent those of my employer.