Online nslookup tools,dig domain ns,fecth NS records,dig hostame ns

This is free online nslookup tool, it's fetch find ns records of domain or hostname. Lookup going fast, you can try to use subdomain and domain names, it showing common and additional sections of information.
You can read related article here - nslookup. Name Server Record. An NS record declares that a given zone is served by a given name server. Every NS record is either a delegation record or an authority Record. If the name of the NS record is the name of the zone it appears in, it is an authority record. An NS record allows you to give authority for managing your domain or subdomain DNS to third-party nameservers. When creating an NS record, the subdomain has a zone file, different than that of the main domain, on the third-party nameserver. One important obstacle, though: When an NS record for a zone refers to a CNAME defined within the zone itself, glue records would be needed in the superior zone just as if the NS record referred to an actual machine name. The NS lookup test performs an NS record (Name Servers record) lookup for a specific domain name, which returns the Name Servers responsible for the domain name records. The test results display the hostnames and IP addresses of the Name Servers.