Results 1 to 7 of 7
Thread: Unusable IP Address
-
11-30-2006, 08:23 PM #1Registered User
- Join Date
- Jun 2004
- Posts
- 139
Unusable IP Address
Why would an Ip address be unusable?
-
11-30-2006, 08:43 PM #2The least among you.
- Join Date
- Apr 2005
- Location
- Jacksonville, FL
- Posts
- 981
In a given subnet (let's say a /29 for example), you have 29 network bits, 3 host bits. Those 3 host bits (one, two, and four, along with all-zeros) added together give 8 possibilities in binary. So a /29, you have 8 total IPs. The bottom IP (network address) and top IP (broadcast address) are technically "illegal" to use per established IP standards (IETF RFCs).
There are some OS's (like Linux) which allow you to use those IPs, in spite of what I said above. An example of an OS that does not allow you to use the top/bottom IPs would be all versions of Windows. You can still use them in Windows only if you change the subnet mask to a bigger mask than your actual allocation. Another example is cPanel; network and broadcast IPs are illegal according to their scripts.
Hope that helps.
Now selling BigVPS's!
Jacksonville Colocation and dedicated servers by colo4jax
We are *not* a reseller. We own our servers, switches, routers and racks.
-
11-30-2006, 09:00 PM #3Retired Moderator
- Join Date
- Nov 2002
- Location
- WebHostingTalk
- Posts
- 8,901
* Moved to Technical and Security Issues...
SiriusI support the Human Rights Campaign!
Moving to the Tampa, Florida area? Check out life in the suburbs in Trinity, Florida.
-
11-30-2006, 09:56 PM #4Junior Guru Wannabe
- Join Date
- Oct 2006
- Posts
- 44
There are also ranges of ip addresses which are reserved of private use. 10.0.0.0/8 is the reserved A class address range, 192.168.0.0 through 192.168.31.255 are private C class networks, and I can never remember the reserved B class addresses. You can use these addresses in a private network, but they won't be accepted on the internet, you'll have to do some type of network address translation (NAT).
Andrew
Spry VPS Hosting cPanel VPS, Plesk VPS, Webmin VPS, Shared, Domain Registration, Dedicated and Colo
VPSLink Cheap VPS accounts CentOS, Fedora 4/5/6, RHEL, Gentoo, Debian, Ubuntu -- Dapper/Edgy, Slackware, OpenSUSE, LAMP + Ruby pre-installed available
-
11-30-2006, 10:00 PM #5Managed Hosting Expert
- Join Date
- Jan 2004
- Location
- North Yorkshire, UK
- Posts
- 4,164
Originally Posted by spryandrew
I think the OP is more referring to what Tical said however regarding network / broadcast addresses.█ Dan Kitchen | Technical Director | Razorblue
█ ddi: (+44) (0)1748 900 680 | e: dkitchen@razorblue.com
█ UK Intensive Managed Hosting, Clusters and Colocation.
█ HP Servers, Cisco/Juniper Powered BGP Network (AS15692).
-
12-01-2006, 01:27 PM #6Registered User
- Join Date
- Jun 2004
- Posts
- 139
Originally Posted by tical
Thanks for the eduation. The reason I ask is because I ordered a dedi box that came with 1 IP. I can purchase an additional 4 for $4 months, but now my host is telling me that I would only get a total of 4.
So I am wondering why one might be unusable now
-
12-01-2006, 03:23 PM #7Web Hosting Master
- Join Date
- Apr 2003
- Location
- NC
- Posts
- 3,093
Originally Posted by Bruin03John W, CISSP, C|EH
MS Information Security and Assurance
ITEagleEye.com - Server Administration and Security
Yawig.com - Managed VPS and Dedicated Servers with VIP Service