Table 2.

Features extracted in this paper for learning

Type	Feature description
Structural	Domain name length, Number of subdomains, Subdomain length mean, Has www prefix, Has valid TLD, Contains single-character subdomain, Is exclusive prefix repetition, Contains TLD as subdomain, Ratio of digit-exclusive subdomains, Ratio of hexadecimal-exclusive subdomains, Underscore ratio, Contains IP address
Linguistic	Contains digits, Vowel ratio, Digit ratio, Alphabet cardinality, Ratio of repeated characters, Ratio of consecutive consonants, Ratio of consecutive digits, Ratio of meaningful words
Statistical	N-gram (N = 1, 2, 3) frequency distribution (mean, standard deviation, median, max, min, the lower quartile, the upper quartile), Entropy