Show Lecture.TopLevelDomains as a slide show.
CT320 Top Level Domains
Top Level Domains Trivia
- As of July 2019, there are 1530 TLDs (Top-Level Domains).
- Longest (ASCII): .NorthWesternMutual, .TravelersInsurance
- There are no single-character TLDs.
- .int: NATO, World Bank, International Criminal Court, Benelux Union, etc.
- .aq:
.eu: .uk/.gb:
.su/.ru:
https://data.iana.org/TLD/tlds-alpha-by-domain.txt
The Original Top-Level Domains
About 1984, the original TLDs were created:
- .com: commerce
- .net: originally network stuff
- .org: originally non-profit organizations
- .edu: educational institutions
- .mil: U.S. military
- .gov: U.S. government
- .int: international organizations
- .arpa: overhead
Country Codes
There are 248 two-letter ASCII country codes, as assigned in ISO 3166-1:
.ac .ad .ae .af .ag .ai .al .am .ao .aq .ar .as .at .au .aw .ax .az .ba .bb .bd .be .bf .bg .bh .bi .bj .bm .bn .bo .br .bs .bt .bv .bw .by .bz .ca .cc .cd .cf .cg .ch .ci .ck .cl .cm .cn .co .cr .cu .cv .cw .cx .cy .cz .de .dj .dk .dm .do .dz .ec .ee .eg .er .es .et .eu .fi .fj .fk .fm .fo .fr .ga .gb .gd .ge .gf .gg .gh .gi .gl .gm .gn .gp .gq .gr .gs .gt .gu .gw .gy .hk .hm .hn .hr .ht .hu .id .ie .il .im .in .io .iq .ir .is .it .je .jm .jo .jp .ke .kg .kh .ki .km .kn .kp .kr .kw .ky .kz .la .lb .lc .li .lk .lr .ls .lt .lu .lv .ly .ma .mc .md .me .mg .mh .mk .ml .mm .mn .mo .mp .mq .mr .ms .mt .mu .mv .mw .mx .my .mz .na .nc .ne .nf .ng .ni .nl .no .np .nr .nu .nz .om .pa .pe .pf .pg .ph .pk .pl .pm .pn .pr .ps .pt .pw .py .qa .re .ro .rs .ru .rw .sa .sb .sc .sd .se .sg .sh .si .sj .sk .sl .sm .sn .so .sr .ss .st .su .sv .sx .sy .sz .tc .td .tf .tg .th .tj .tk .tl .tm .tn .to .tr .tt .tv .tw .tz .ua .ug .uk .us .uy .uz .va .vc .ve .vg .vi .vn .vu .wf .ws .ye .yt .za .zm .zw
Non-country geographic domains
In addition to the two-letter country code domains, there are a growing number of geographic domains, including:
- Continents: .africa .asia
- Regions: .cat .lat
- Cities: .hamburg .nyc .paris .vegas
- Other: .eu .quebec .scot
https://wikipedia.org/wiki/List_of_Internet_top-level_domains#Geographic_top-level_domains
.US
Unfortunately, .us is a disaster, due to the overly-complex naming scheme enforced until 2002:
- Colorado: https://state.co.us
- That fails, but http://www.state.co.us forwards to https://colorado.gov/
- Larimer county: https://co.larimer.co.us
- That forwards to https://www.larimer.org
- Fort Collins: https://ci.fortcollins.co.us
- That fails. Surprise—it’s https://fcgov.com
That’s one .gov, one .org, and one .com. Uniformity!
Map
Second Wave
In the early 2000s, several TLDs were added:
Speculation
As of October 2017, applin.com was available for $3,495 00.
Non-International Domains
We are in a speculation bubble, as top-level domains are being sold for $$$. Current top-level domains:
.aaa
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.aarp
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.abb .abbott
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.abbvie .abc .able .abogado
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.abudhabi
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.ac
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.academy .accenture
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.accountant
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.accountants
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.aco .actor
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.ad .ads .adult .ae .aeg .aero .aetna .af .afl .africa .ag .agakhan .agency .ai .aig .airbus .airforce .airtel .akdn .al .alibaba .alipay .allfinanz .allstate .ally .alsace .alstom .am .amazon .americanexpress
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.americanfamily
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.amex .amfam .amica .amsterdam .analytics .android .anquan .anz .ao .aol .apartments .app .apple .aq .aquarelle .ar .arab .aramco .archi .army .arpa .art .arte .as .asda .asia .associates .at .athleta .attorney .au .auction .audi .audible .audio .auspost .author .auto .autos .aw .aws .ax .axa .az .azure .ba .baby .baidu .banamex .band .bank .bar .barcelona .barclaycard .barclays .barefoot .bargains .baseball .basketball .bauhaus .bayern .bb .bbc .bbt .bbva .bcg .bcn .bd .be .beats .beauty .beer .berlin .best .bestbuy .bet .bf .bg .bh .bharti .bi .bible .bid .bike .bing .bingo .bio .biz .bj .black .blackfriday .blockbuster .blog .bloomberg .blue .bm .bms .bmw .bn .bnpparibas .bo .boats .boehringer .bofa .bom .bond .boo .book .booking .bosch .bostik .boston .bot .boutique .box .br .bradesco .bridgestone .broadway .broker .brother .brussels .bs .bt .build .builders .business .buy .buzz .bv .bw .by .bz .bzh .ca .cab .cafe .cal .call .calvinklein .cam .camera .camp .canon .capetown .capital .capitalone .car .caravan .cards .care .career .careers .cars .casa .case .cash .casino .cat .catering .catholic .cba .cbn .cbre .cc .cd .center .ceo .cern .cf .cfa .cfd .cg .ch .chanel .channel .charity .chase .chat .cheap .chintai .christmas .chrome .church .ci .cipriani .circle .cisco .citadel .citi .citic .city .ck .cl .claims .cleaning .click .clinic .clinique .clothing .cloud .club .clubmed .cm .cn .co .coach .codes .coffee .college .cologne .com .commbank .community .company .compare .computer .comsec .condos .construction
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.consulting .contact .contractors .cooking .cool .coop .corsica .country .coupon .coupons .courses .cpa .cr .credit .creditcard .creditunion .cricket .crown .crs .cruise .cruises .cu .cuisinella .cv .cw .cx .cy .cymru .cyou .cz .dad .dance .data .date .dating .datsun .day .dclk .dds .de .deal .dealer .deals .degree .delivery .dell .deloitte .delta .democrat .dental .dentist .desi .design .dev .dhl .diamonds .diet .digital .direct .directory .discount .discover .dish .diy .dj .dk .dm .dnp .do .docs .doctor .dog .domains .dot .download .drive .dtv .dubai .dupont .durban .dvag .dvr .dz .earth .eat .ec .eco .edeka .edu .education .ee .eg .email .emerck .energy .engineer .engineering .enterprises .epson .equipment .er .ericsson .erni .es .esq .estate .et .eu .eurovision .eus .events .exchange .expert .exposed .express .extraspace .fage .fail .fairwinds .faith .family .fan .fans .farm .farmers .fashion .fast .fedex .feedback .ferrari .ferrero .fi .fidelity .fido .film .final .finance .financial .fire .firestone .firmdale .fish .fishing .fit .fitness .fj .fk .flickr .flights .flir .florist .flowers .fly .fm .fo .foo .food .football .ford .forex .forsale .forum .foundation .fox .fr .free .fresenius .frl .frogans .frontier .ftr .fujitsu .fun .fund .furniture .futbol .fyi .ga .gal .gallery .gallo .gallup .game .games .gap .garden .gay .gb .gbiz .gd .gdn .ge .gea .gent .genting .george .gf .gg .ggee .gh .gi .gift .gifts .gives .giving .gl .glass .gle .global .globo .gm .gmail .gmbh .gmo .gmx .gn .godaddy .gold .goldpoint .golf .goodyear .goog .google .gop .got .gov .gp .gq .gr .grainger .graphics .gratis .green .gripe .grocery .group .gs .gt .gu .gucci .guge .guide .guitars .guru .gw .gy .hair .hamburg .hangout .haus .hbo .hdfc .hdfcbank .health .healthcare .help .helsinki .here .hermes .hiphop .hisamitsu .hitachi .hiv .hk .hkt .hm .hn .hockey .holdings .holiday .homedepot .homegoods .homes .homesense .honda .horse .hospital .host .hosting .hot .hotels .hotmail .house .how .hr .hsbc .ht .hu .hughes .hyatt .hyundai .ibm .icbc .ice .icu .id .ie .ieee .ifm .ikano .il .im .imamat .imdb .immo .immobilien .in .inc .industries .infiniti .info .ing .ink .institute .insurance .insure .int .international
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.intuit .investments .io .ipiranga .iq .ir .irish .is .ismaili .ist .istanbul .it .itau .itv .jaguar .java .jcb .je .jeep .jetzt .jewelry .jio .jll .jm .jmp .jnj .jo .jobs .joburg .jot .joy .jp .jpmorgan .jprs .juegos .juniper .kaufen .kddi .ke .kerryhotels .kerryproperties .kfh .kg .kh .ki .kia .kids .kim .kindle .kitchen .kiwi .km .kn .koeln .komatsu .kosher .kp .kpmg .kpn .kr .krd .kred .kuokgroup .kw .ky .kyoto .kz .la .lacaixa .lamborghini .lamer .land .landrover .lanxess .lasalle .lat .latino .latrobe .law .lawyer .lb .lc .lds .lease .leclerc .lefrak .legal .lego .lexus .lgbt .li .lidl .life .lifeinsurance .lifestyle .lighting .like .lilly .limited .limo .lincoln .link .live .living .lk .llc .llp .loan .loans .locker .locus .lol .london .lotte .lotto .love .lpl .lplfinancial .lr .ls .lt .ltd .ltda .lu .lundbeck .luxe .luxury .lv .ly .ma .madrid .maif .maison .makeup .man .management .mango .map .market .marketing .markets .marriott .marshalls .mattel .mba .mc .mckinsey .md .me .med .media .meet .melbourne .meme .memorial .men .menu .merckmsd .mg .mh .miami .microsoft .mil .mini .mint .mit .mitsubishi .mk .ml .mlb .mls .mm .mma .mn .mo .mobi .mobile .moda .moe .moi .mom .monash .money .monster .mormon .mortgage .moscow .moto .motorcycles .mov .movie .mp .mq .mr .ms .msd .mt .mtn .mtr .mu .museum .music .mv .mw .mx .my .mz .na .nab .nagoya .name .navy .nba .nc .ne .nec .net .netbank .netflix .network .neustar .new .news .next .nextdirect .nexus .nf .nfl .ng .ngo .nhk .ni .nico .nike .nikon .ninja .nissan .nissay .nl .no .nokia .norton .now .nowruz .nowtv .np .nr .nra .nrw .ntt .nu .nyc .nz .obi .observer .office .okinawa .olayan .olayangroup .ollo .om .omega .one .ong .onl .online .ooo .open .oracle .orange .org .organic .origins .osaka .otsuka .ott .ovh .pa .page .panasonic .paris .pars .partners .parts .party .pay .pccw .pe .pet .pf .pfizer .pg .ph .pharmacy .phd .philips .phone .photo .photography .photos .physio .pics .pictet .pictures .pid .pin .ping .pink .pioneer .pizza .pk .pl .place .play .playstation .plumbing .plus .pm .pn .pnc .pohl .poker .politie .porn .post .pr .praxi .press .prime .pro .prod .productions .prof .progressive .promo .properties .property .protection .pru .prudential .ps .pt .pub .pw .pwc .py .qa .qpon .quebec .quest .racing .radio .re .read .realestate .realtor .realty .recipes .red .redumbrella .rehab .reise .reisen .reit .reliance .ren .rent .rentals .repair .report .republican .rest .restaurant .review .reviews .rexroth .rich .richardli .ricoh .ril .rio .rip .ro .rocks .rodeo .rogers .room .rs .rsvp .ru .rugby .ruhr .run .rw .rwe .ryukyu .sa .saarland .safe .safety .sakura .sale .salon .samsclub .samsung .sandvik .sandvikcoromant .sanofi .sap .sarl .sas .save .saxo .sb .sbi .sbs .sc .scb .schaeffler .schmidt .scholarships .school .schule .schwarz .science .scot .sd .se .search .seat .secure .security .seek .select .sener .services .seven .sew .sex .sexy .sfr .sg .sh .shangrila .sharp .shell .shia .shiksha .shoes .shop .shopping .shouji .show .si .silk .sina .singles .site .sj .sk .ski .skin .sky .skype .sl .sling .sm .smart .smile .sn .sncf .so .soccer .social .softbank .software .sohu .solar .solutions .song .sony .soy .spa .space .sport .spot .sr .srl .ss .st .stada .staples .star .statebank .statefarm .stc .stcgroup .stockholm .storage .store .stream .studio .study .style .su .sucks .supplies .supply .support .surf .surgery .suzuki .sv .swatch .swiss .sx .sy .sydney .systems .sz .tab .taipei .talk .taobao .target .tatamotors .tatar .tattoo .tax .taxi .tc .tci .td .tdk .team .tech .technology .tel .temasek .tennis .teva .tf .tg .th .thd .theater .theatre .tiaa .tickets .tienda .tips .tires .tirol .tj .tjmaxx .tjx .tk .tkmaxx .tl .tm .tmall .tn .to .today .tokyo .tools .top .toray .toshiba .total .tours .town .toyota .toys .tr .trade .trading .training .travel .travelers .travelersinsurance
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| length | count |
|---|---|
| 2 | 248 |
| 3 | 215 |
| 4 | 205 |
| 5 | 154 |
| 6 | 158 |
| 7 | 123 |
| 8 | 78 |
| 9 | 41 |
| 10 | 30 |
| 11 | 21 |
| 12 | 4 |
| 13 | 3 |
| 14 | 2 |
| 15 | 3 |
| 18 | 1 |
Punycode
DNS requires ASCII-only. However, the Punycode encoding scheme allows for domains in all languages, e.g., Chinese, Arabic, Hindi, etc.
Here are several examples.
Reserved
| Reserved Domain | Says Who |
|---|---|
| .example | RFC 6761 |
| .example.com | RFC 6761 |
| .example.net | RFC 6761 |
| .example.org | RFC 6761 |
| .invalid | RFC 6761 |
| .localhost | RFC 6761 |
| .test | RFC 6761 |
| .local | RFC 6762 |
| .onion | RFC 7686 |
There are also reserved IP addresses.



