在线检测域名是否合法

import re

def is_valid_domain(domain):
    pattern = r'^([a-zA-Z0-9]+(-?[a-zA-Z0-9]+)*\.)+[a-zA-Z]{2,}$'
    return re.match(pattern, domain) is not None

# 示例
print(is_valid_domain("example.com"))  # True
print(is_valid_domain("example..com")) # False

import requests

def check_domain_availability(domain):
    api_url = "https://api.domain.com/check"
    params = {'domain': domain}
    response = requests.get(api_url, params=params)
    if response.status_code == 200:
        data = response.json()
        return data['available']
    return False

# 示例
print(check_domain_availability("example.com"))  # False

import dns.resolver

def check_dns_resolution(domain):
    try:
        answers = dns.resolver.resolve(domain, 'A')
        return True
    except dns.resolver.NXDOMAIN:
        return False
    except dns.resolver.NoAnswer:
        return False
    except dns.resolver.Timeout:
        return False

# 示例
print(check_dns_resolution("example.com"))  # True or False