IP blocking and especially IP range blocking is the built-in MediaWiki functionality that allows sysops to block particular IP numbers, preventing anybody using these IPs from editing.
Wikipedia recommends that "IP addresses should almost never be indefinitely blocked". Additionally, it notes on the subject of range blocks that one should use "careful judgement and make them as brief as possible; this can affect over sixty-five thousand IP addresses (65,534, to be precise), potentially affecting millions of users." As of June 2009, over 20,000,000 IP addresses have been blocked by Conservapedia. Since then it's got worse - they've been adding to the range blocked addresses in a big way.
The policy for the length of the
derange d blocks is not clear: some sysops tend to block for six months or a year, other only issue infinite ones.
An IP (internet protocol) address, is in some ways similar to a house address, it tells a computer where on the internet an object is operating, be it router, webserver etc.
What does "/16" mean?
The long answer can be found in the Range block manual. It also includes the "Idiot's guide to range blocks", which nicely breaks down some of the technical aspects.
The short answer is that (using Andy's test block as an example) "126.96.36.199/16" blocks all IP addresses starting with "142.167". Or, to put it into an often-used form: "142.167.*.*" will be blocked.
As mentioned above, blocking IP addresses like this prevents all editors in these ranges from editing on CP. Now, that wouldn't be so bad, if the range was small enough. Unfortunately, "188.8.131.52/16" is a range containing 65,534 individual IPs.
...and what about "/8"?
Counter-intuitively, "/8" covers a wider range than "/16".
Sticking to the example above, "184.108.40.206/16" would cover "142.167.*.*" (equalling 65,534 IPs). "220.127.116.11/8" however would cover "142.*.*.*" (equalling 16,777,214 IPs).
To prevent people from doing really dumb things, the MediaWiki software does not allow anything worse than "/16" blocks.
The "/24" range covers 254 IPs - the range of the fourth number of an IP. So "18.104.22.168/24" covers "142.167.11.*". It's a more precise range than "/16" and should be the preferred choice of the two for normal cases.
Formally, there is no "/32" range, as this covers only one number.
On the other end, "/0" means every IP address available -- if it was possible for these guys to block x.y.z.w/0 it would effectively render CP read-only.
List of range blocks
|IPs in Range||65536||32768||16384||8192||4096||2048||1024||512||256||128||64||32||16||8||4||2||1|
|# ∞ Blocks||138||0||2||0||0||0||28||2||89||0||0||0||0||0||0||0||588|
- A chunk of Level3 Communications - a backbone internet ISP. Hard to nail down to a particular location as they own all of 22.214.171.124/8. From this address space they license it out to other local ISPs and large companies across the world.
- Whoops, User:Linus apparently got ownz'd...
- Part of AT&T, though a very small part. AT&T owns all of 126.96.36.199/8
- The first /24 block to be done. Part of MIT, which owns all of 188.8.131.52/8
- A bot ip, that spammed Question Evolution.png everywhere. Owned by of Telus Communications.
- Allegedly connected to Icewedge.
- Road Runner HoldCo LLC of Herndon, VA - Another strike at the government center
- An IP in this range was used by cp:User:Jayjay
- Comcast from Miami.
- Eastlink from Halifax, Nova Scotia.
- Allegedly connected to the Halifax Troll, blocked for 6 months
- Herndon, VA. If you toss this into Google maps, you will see that Conservapedia is on its way to banning the center of the United States Government.
- A part of AOL - though AOL owns all of 184.108.40.206/16.
- Part of Optimum Online in... Hicksville, NY. Certainly there is at least one conservative there
- Proxy sites such as HideMyAss.com feel the Thor-like banhammer power of sysop Karajou.
- Cox Communications Inc. of Atlanta, GA. Though this is only a fraction of the network that company owns there.
- Hicksville, NY. again...
220.127.116.11/16 A banhammer arrow Deep in the Heart of Texas, (Dallas), (1 vandal expunged, 65,535 other IP's taken "care of".)Undid @3:12 EDT
- Montreal area.
- Part of Rogers Cable Communications, Inc, of Toronto, Canada. The company owns all of 18.104.22.168/16.
- Small part of Windstream Broadband. Has been blocked as a "troll proxy" for 6 months.
- Charter Communications , St Louis.
- Road Runner HoldCo LLC NetRange: 22.214.171.124 - 126.96.36.199 ?
- Part of Virgin Broadband, UK
- Telecom Italia.TK blocked for 3 month with a reason of "retail dynamic"
- Freenet, a German ISP. TK blocked for 3 months claiming it is a "German proxy"
- Part of Purdue University. TK blocked it for 3 days, a block that has since expired.
- University of Karlsruhe 
- University of Cincinnati 
- Sydney, NS
- Saint John, NB
- This IP had been the subject of Andy's initial test. It was later turned into a permanent block.
- Halifax, Nova Scotia
- Stentor National Integrated Communications Network of Ottawa, ON 
- Halifax, Nova Scotia
- A section of UNINET's network, listed as Cape Town, in South Africa. TK blocked it for a month, calling it a 'troll server' 
- Texas A&M a noted Lib'ral haven.
- Mostly, several universities in Great Britain with a few research institutes thrown in for seasoning. 
- Naval Air Systems Command, VA 
- USDA Office of Operations, Fort Collins CO. Blocked by Hojimachong, unblocked by TK
- Part of Asia - possibly Vietnam.
- Part of AOL 
- Supposedly "KPU Telecommunications, Ketchikan, AK" actually covers a variety of companies, government organizations, and schools, including the Las Vegas Police Dept.  TK blocked it for 3 months.
- RCN Corporation of... Herndon, VA. Again.
- CAIS Internet and Pinnacle Online. Blocked by Hojimachong, unblocked by TK
- Fuse Internet Access of Cincinnati, OH
- An IP in this range was used by cp:User:Stevecarson and cp:User:Jazzman831
- And unblocked by Andy
- A bit of Alaska. This block includes a several high schools and a cyber school. 
- Compañía Dominicana de Teléfonos, Dominican Republic
- Univ of Illinois
- University of Alaska (What Would Palin Say?)
Within the first 5 days of September, TK issued the following long-term range blocks:
- 188.8.131.52/16 - 1 year - Kirkland & Ellis LLP, Chicago,
- 184.108.40.206/16 - 6 months - OUK Broadband IP Stream, U.K.
220.127.116.11/16 - 1 year - M-NET TELEKOMMUNIKATIONS GMBH, Munich, Germany
- 18.104.22.168/16 - 1 year - Videotron Ltee (C00503859) Quebec, Canada
22.214.171.124/19 - 1 year - TELUS Communications Inc, BC, Canada(Unblocked by RobS on 6/13/2011)
- 126.96.36.199/16 - 6 months - FRANCE TELECOM/SCR
- 188.8.131.52/16 - 6 months - BT-CENTRAL-PLUS
184.108.40.206/16 - 1 year - Deutsche Telekom AG, Germany
- 220.127.116.11/18 - 1 year - Steadfast Networks, Chicago, IL
- 18.104.22.168/17 - 1 year - SAVONLINNAN PUHELIN OY HILIMANET SERVICES, Finland
22.214.171.124/16 - 1 year - Global Infrastructure Group Global Infrastructure Group(Unblocked by RobS on 6/13/2011)
In contrast, Karajou did not issue a single range block, whereas in 5 days TK has prevented some 704,000 IP addresses from editing on Conservapedia.
IPs per sysop
All blocks are of the "/16" sort unless noted otherwise.
- Karajou: 12 blocks - 786,432 individual IPs
- TK: 10 blocks - 655,360 individual IPs
- Andy: 4 blocks - 262,144 individual IPs
- Hojimachong: 1 block - 65,536 individual IPs
NiandraJallen: 3 /24 blocks - 765 individual IPs
- Total: 1,769,982 and counting...
Conservapedia has blocked more than 11,000,000 individual IPs. Because some of the blocks have expired, on Jan 13th, 2009, there were just 6,000,000 individual IPs blocked - roughly 0.144 % of the net. The following pic shows the blocked IPs: the x-coordinate is the first octet of a address, the y-coordinate the second one, so a single point represents 65,536 addresses. If only one of these addresses is blocked, the point is colored white, the darker the point, the more addresses are taken out: black indicates that all addresses are blocked. Light blue points are not blocked at all, while dark blue points represent special IP addresses, as 127.0.0.0 .
- Blocking IP addresses, "Blocking IP addresses", section "Block lengths" on Wikipedia
- "Blocking IP addresses", section "Range blocks" on Wikipedia
- Range blocks on Meta.Wikipedia.org - permalink because the page now redirects to a slightly more technical version
- Post on User talk:Aschlafly
- Herndon, VA on Google Maps
- Block log
- Post on User talk:Aschlafly
- Post on user talk:Aschlafly
- Post on user talk:aschlafly
- Block log for range