Please note that this function requires an updated variable named $domainsDictionary. Since LTD’s are being expanded at a very fast pace, the given example may not work for new domain names that are NEW and not included in the expired variable. Hence, to production code should pull this variable from an authoritative source such as InterNIC / ICANN. Following is ‘playaround’ code that shouldn’t be used in ‘production’ scripts.

# getRootDomainFromUrl.ps1
# This solves the problem of extracting the root domain from a URL
# The challenge here is to incorporate semantics of incorporating the array of TLDs during extraction

$url='https://intranet.kimconnect.co.uk'
$domainsDictionary=@{
    '.ac'='Ascension Island'
    '.ac.uk'='Second-level domain for United Kingdom (.uk) and most often used for academic sites.'
    '.ad'='Andorra'
    '.ae'='United Arab Emirates'
    '.aero'='Air Transportation Industry'
    '.af'='Afghanistan'
    '.ag'='Antigua and Barbuda'
    '.ai'='Anguilla'
    '.al'='Albania'
    '.am'='Armenia'
    '.an'='Netherlands Antilles'
    '.ao'='Angola'
    '.aq'='Antarctica'
    '.ar'='Argentina'
    '.arpa'='Internet infrastructure TLD'
    '.as'='American Somoa'
    '.asia'='Asian countries'
    '.at'='Austria'
    '.au'='Australia'
    '.aw'='Aruba'
    '.ax'='Aland Islands - part of Finland'
    '.az'='Azerbaijan'
    '.ba'='Bosnia and Herzegovinia'
    '.bb'='Barbados'
    '.bd'='Bangladesh'
    '.be'='Belgium'
    '.bf'='Burkina Faso'
    '.bg'='Bulgaria'
    '.bh'='Bahrain'
    '.bi'='Burundi'
    '.biz'='United States business site.'
    '.bj'='Benin'
    '.bm'='Bermuda'
    '.bn'='Brunei Darussalam'
    '.bo'='Bolivia'
    '.br'='Brazil'
    '.bs'='Bahamas'
    '.bt'='Bhutan'
    '.bv'='Bouvet Island'
    '.bw'='Botswana'
    '.by'='Belarus and Byelorussia'
    '.bz'='Belize'
    '.ca'='Canada'
    '.cat'='Catalan'
    '.cc'='Cocos Islands - Keelings'
    '.cd'='Democratic Republic of the Congo'
    '.cf'='Central African Republic'
    '.cg'='Congo'
    '.ch'='Switzerland'
    '.ci'='Cote dIvoire'
    '.ck'='Cook Islands'
    '.cl'='Chile'
    '.cm'='Cameroon'
    '.cn'='China'
    '.co'='Colombia'
'.co.in'='Second-level domain for India (.in) and most often used for commercial sites.'
'.co.jp'='Second-level domain for Japan (.jp) and most often used for commercial sites.'
'.co.kr'='Second-level domain for Korea (.kr) and most often used for commercial sites.'
'.com.mx'='Mexico commercial website.'
'.com.co'='Columbia commercial website.'
'.com.eg'='Egypt commercial website.'
'.com.ua'='Ukraine commercial website.'
'.com.au'='Australia commercial website.'
'.com.hk'='Hong Kong commercial website.'
'.com.ln'='Lebanese commercial website.'
'.com.tr'='Turkey commercial website.'
    '.co.uk'='Second-level domain for United Kingdom (.uk) and most often used for commercial sites.'
    '.com'='United States commercial website.'
    '.com.br'='Brazil commercial website.'
    '.coop'='Business cooperatives and organizations.'
    '.cr'='Costa Rica'
    '.cs'='Former Czechoslovakia'
    '.cu'='Cuba'
    '.cv'='Cape Verde'
    '.cw'='Curaçao'
    '.cx'='Christmas Island'
    '.cy'='Cyprus'
    '.cz'='Czech Republic'
    '.dd'='East Germany'
    '.de'='Germany'
    '.dj'='Djibouti'
    '.dk'='Denmark'
    '.dm'='Dominica'
    '.do'='Dominican Republic'
    '.dz'='Algeria'
    '.ec'='Ecuador'
    '.edu'='United States education site.'
    '.ee'='Estonia'
    '.eg'='Egypt'
    '.eh'='Western Sahara'
    '.er'='Eritrea'
    '.es'='Spain'
    '.et'='Ethiopia'
    '.eu'='European Union'
    '.fi'='Finland'
    '.firm'='Internet site for business or firm.'
    '.fj'='Fiji'
    '.fk'='Falkland Islands and Malvinas'
    '.fm'='Micronesia'
    '.fo'='Faroe Islands'
    '.fr'='France'
    '.fx'='Metropolitan France'
    '.ga'='Gabon'
    '.gb'='Great Britain'
    '.gd'='Grenada'
    '.ge'='Georgia'
    '.gf'='French Guiana'
    '.gg'='Guernsey'
    '.gh'='Ghana'
    '.gi'='Gibraltar'
    '.gl'='Greenland'
    '.gm'='Gambia'
    '.gn'='Guinea'
    '.gov'='United States Government site.'
    '.gov.uk'='Second-level domain for United Kingdom (.uk) and most often used for government sites.'
    '.gp'='Guadeloupe'
    '.gq'='Equatorial Guinea'
    '.gr'='Greece'
    '.gs'='South Georgia and South Sandwich Islands.'
    '.gt'='Guatemala'
    '.gu'='Guam'
    '.gw'='Guinea-Bissau'
    '.gy'='Guyana'
    '.hk'='Hong Kong'
    '.hm'='Heard and McDonald Islands'
    '.hn'='Honduras'
    '.hr'='Croatia/Hrvatska'
    '.ht'='Haiti'
    '.hu'='Hungary'
    '.id'='Indonesia'
    '.ie'='Ireland'
    '.il'='Israel'
    '.im'='Isle of Man'
    '.in'='India'
    '.info'='United States information site with no restrictions.'
    '.int'='International institute site.'
    '.io'='British Indian Ocean Territory'
    '.iq'='Iraq'
    '.ir'='Iran'
    '.is'='Iceland'
    '.it'='Italy'
    '.je'='Jersey - Channel Islands a UK dependency'
    '.jm'='Jamaica'
    '.jo'='Jordan'
    '.jobs'='Job related sites.'
    '.jp'='Japan'
    '.ke'='Kenya'
    '.kg'='Kyrgyzstan'
    '.kh'='Cambodia'
    '.ki'='Kiribati'
    '.km'='Comoros'
    '.kn'='Saint Kitts and Nevis'
    '.kp'='North Korea'
    '.kr'='South Korea'
    '.kw'='Kuwait'
    '.ky'='Cayman Islands'
    '.kz'='Kazakhstan'
    '.la'='Laos'
    '.lb'='Lebanon'
    '.lc'='Saint Lucia'
    '.li'='Liechtenstein'
    '.lk'='Sri Lanka'
    '.lr'='Liberia'
    '.ls'='Lesotho'
    '.lt'='Lithuania'
    '.ltd.uk'='Second-level domain for United Kingdom (.uk) and most often used for limited company sites.'
    '.lu'='Luxembourg'
    '.lv'='Latvia'
    '.ly'='Libya'
    '.ma'='Morocco'
    '.mc'='Monaco'
    '.md'='Moldova'
    '.me'='Montenegro'
    '.me.uk'='Second-level domain for United Kingdom (.uk) and most often used for personal sites.'
    '.mg'='Madagascar'
    '.mh'='Marshall Islands'
    '.mil'='United States Military site.'
    '.mk'='Macedonia'
    '.ml'='Mali'
    '.mm'='Myanmar'
    '.mn'='Mongolia'
    '.mo'='Macau'
    '.mobi'='Mobile devices'
    '.mod.uk'='Second-level domain for United Kingdom (.uk) and most often used for military of defence sites.'
    '.mp'='Northern Mariana Islands'
    '.mq'='Martinique'
    '.mr'='Mauritania'
    '.ms'='Montserrat'
    '.mt'='Malta'
    '.mu'='Mauritius'
    '.museum'='Worldwide museums'
    '.mv'='Maldives'
    '.mw'='Malawi'
    '.mx'='Mexico'
    '.my'='Malaysia'
    '.mz'='Mozambique'
    '.na'='Namibia'
    '.name'='Individual and family names'
    '.nato'='NATO site.'
    '.nc'='New Caledonia'
    '.ne'='Niger'
    '.net'='United States Internet administrative site. See the .net definition for alternative definitions.'
    '.net.uk'='Second-level domain for United Kingdom (.uk) and most often used for network company sites.'
    '.nf'='Norfolk Island'
    '.ng'='Nigeria'
    '.nhs.uk'='Second-level domain for United Kingdom (.uk) and most often used for national health service institutions'
    '.ni'='Nicaragua'
    '.nl'='Netherlands'
    '.no'='Norway'
    '.nom'='Personal site'
    '.np'='Nepal'
    '.nr'='Nauru'
    '.nt'='Neutral Zone'
    '.nu'='Niue'
    '.nz'='New Zealand'
    '.om'='Oman'
    '.org'='Organization (non-profit) sites.'
    '.org.uk'='Second-level domain for United Kingdom (.uk) and most often used for non-profit sites.'
    '.pa'='Panama'
    '.pe'='Peru'
    '.pf'='French Polynesia'
    '.pg'='Papua New Guinea'
    '.ph'='Philippines'
    '.pk'='Pakistan'
    '.pl'='Poland'
    '.plc.uk'='Second-level domain for United Kingdom (.uk) and most often used for public limited company sites.'
    '.pm'='St. Pierre and Miquelon'
    '.pn'='Pitcairn'
    '.post'='sTLD (sponsored top-level domain) available exclusively for the postal sector.'
    '.pr'='Puerto Rico'
    '.pro'='United States professional site for accountants'
    '.ps'='Palestinian territories'
    '.pt'='Portugal'
    '.pw'='Palau'
    '.py'='Paraguay'
    '.qa'='Qatar'
    '.re'='Reunion'
    '.ro'='Romania'
    '.rs'='Republic of Serbia'
    '.ru'='Russian Federation'
    '.rw'='Rwanda'
    '.sa'='Saudi Arabia'
    '.sb'='Solomon Islands'
    '.sc'='Seychelles'
    '.sch.uk'='Second-level domain for United Kingdom (.uk) and most often used for school sites.'
    '.sd'='Sudan'
    '.se'='Sweden'
    '.sg'='Singapore'
    '.sh'='Saint Helena'
    '.si'='Slovenia'
    '.sj'='Svalbard and Jan Mayen Islands'
    '.sk'='Slovakia'
    '.sl'='Sierra Leone'
    '.sm'='San Marino'
    '.sn'='Senegal'
    '.so'='Somalia'
    '.sr'='Suriname'
    '.ss'='South Sudan'
    '.st'='Sao Tome and Principe'
    '.store'='United States domain for retail business site.'
    '.su'='Former USSR'
    '.sv'='El Salvador'
    '.sy'='Syria'
    '.sz'='Swaziland'
    '.tc'='Turks and Caicos Islands'
    '.td'='Chad'
    '.tel'='Internet communication services'
    '.tf'='French Southern Territory and Antarctic Lands.'
    '.tg'='Togo'
    '.th'='Thailand'
    '.tj'='Tajikistan'
    '.tk'='Tokelau'
    '.tl'='East Timor'
    '.tm'='Turkmenistan'
    '.tn'='Tunisia'
    '.to'='Tonga'
    '.tp'='East Timor'
    '.tr'='Turkey'
    '.travel'='Travel related sites.'
    '.tt'='Trinidad and Tobago'
    '.tv'='Tuvalu'
    '.tw'='Taiwan'
    '.tz'='Tanzania'
    '.ua'='Ukraine'
    '.ug'='Uganda'
    '.uk'='United Kingdom'
    '.um'='United States minor outlying islands.'
    '.us'='United States'
    '.uy'='Uruguay'
    '.uz'='Uzbekistan'
    '.va'='Vatican City State'
    '.vc'='Saint Vincent and the Grenadines'
    '.ve'='Venezuela'
    '.vg'='British Virgin Islands'
    '.vi'='United States Virgin Islands'
    '.vn'='Vietnam'
    '.vu'='Vanuatu'
    '.web'='Internet site about the World Wide Web.'
    '.wf'='Wallis and Futuna Islands'
    '.ws'='Samoa'
    '.xxx'='Adult entertainment domain'
    '.ye'='Yemen'
    '.yt'='Mayotte'
    '.yu'='Yugoslavia'
    '.za'='South Africa'
    '.zm'='Zambia'
    '.zr'='Zaire'
    '.zw'='Zimbabwe'
}

function getRootDomain($url){
    $domain=([uri]$url).Host
    $matchedTwoDottedDomain=$domainsDictionary.keys|?{$domain -match "$_$"}|?{$_ -match '\.\w+\.'}
    $rootDomain=if(!$matchedTwoDottedDomain){
  #$domain.split('.')[-3]+'.'+($domain.split('.')[-2..-1] -join '.')
  $domain.split('.')[-2..-1] -join '.'
  }else{$domain.split('.')[-3..-1] -join '.'}
    return $rootDomain
}

getRootDomain $url
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