export declare function isFQDN(input: unknown, options?: FQDNOptions): boolean;
export interface FQDNOptions {
    /**
     * Require a top-level domain (TLD)
     * @default true
     */
    requireTld?: boolean;
    /**
     * Allow underscores in domain parts
     * @default false
     */
    allowUnderscores?: boolean;
    /**
     * Allow a trailing dot at the end of the domain
     * @default false
     */
    allowTrailingDot?: boolean;
    /**
     * Allow numeric top-level domains
     * @default false
     */
    allowNumericTld?: boolean;
    /**
     * Allow wildcard domains (starting with *.）
     * @default false
     */
    allowWildcard?: boolean;
    /**
     * Ignore maximum length restrictions for domain parts
     * @default false
     */
    ignoreMaxLength?: boolean;
}