Checks if a given domain is valid according to these tests

C# Domain Validator method.cs

// This will make the following conditions true:
// 1) Does not match hostnames
// 2) Cannot start or end with a dot
// 3) Cannot start or end with a hyphen
// 4) Number 3 applies for the hostname as well
// 5) Two punctuations after each other is not allowed
// 6) Cannot be an IP address
// 7) Can only use the characters: [0-9A-Za-z], punctuations, and hyphens

/*
 * CHECK THIS OUT: https://dotnetfiddle.net/zjg3Ep
 */
 
private bool IsDomainValid(string DomainName)
{
    //no hostnames
    if (DomainName.Split('.').Length <= 1) return false;

    //cannot start or end with a dot - simply invalid
    if (DomainName[0] == '.' || DomainName[DomainName.Length - 1] == '.') return false;

    //cannot start or end with a hyphen - simply invalid
    if (DomainName[0] == '-' || DomainName[DomainName.Length - 1] == '-') return false;

    //hostname cannot start or end with a hyphen - simply invalid
    if (DomainName.Split('.')[0] == "-" || DomainName.Split('.')[0][DomainName.Split('.')[0].Length - 1] == '-') return false;

    //cannot have two dots right after eachother
    if (DomainName.Matches($"[\\.]{2}")) return false;

    //cannot be an IP
    if (Uri.CheckHostName(DomainName) == UriHostNameType.IPv4) return false;

    //cannot contain illegal characters
    if (!DomainName.Matches($"^[a-zA-Z_0-9.-]+$")) return false;

    return true;
}

Got any updates to improve this, let me know. Also make sure to check this out: https://dotnetfiddle.net/zjg3Ep