extract hostnames

im looking for a script that can extract hostnames from a
list(txt,html) like this:

the-roadside.com 3 43197 1( 0)
202.218.17.12-OK
adsvr1.emome.net 25 3391 1( 0)
211.79.36.59-OK
ads.b10f.jp 44 2104 1( 0)
58.4.47.114-OK
ads.topfong.com 46 79977 3( 0)
61.63.4.232-OK 61.63.4.231-OK 61.63.4.230-OK
ad***.topfong.com 46 79978 1( 0)
61.63.4.242-OK
adstat3.kkman.com.tw 53 59 1( 0)
210.200.247.112-OK
ads.pointroll.com 186 48 1( 0)
66.216.104.176-OK
global.msads.net 287 -57 2( 0)
210.201.139.93-OK 80.81.66.93-OK
ads.veryhuman.com 712 83084 1( 0)
219.84.160.198-OK

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