Recently it was brought to my attention that the domain name hashemian.com has a DNS error associated with it. The domain's DNS is hosted with its registrar as many registrars provide basic DNS service for free. This service generally consists of two name servers with varying degrees of restrictions to configure zones and records.
Concerned, I headed to dnscheck.pingdom.com to verify this for myself and indeed the tool does show an SOA records inconsistency error for the domain along with a couple of warnings.
The warnings are attributed to the fact that the name servers do not have reverse addresses (PTR records) associated with them. Having reverse addresses is not a requirement but it is recommended.
Having consistent SOA (Start Of Authority) records on all name servers is however required. Except that in this case the inconsistency reported was only due to upper and lower case differences between the records on the two name servers and that gets into a bit of an unknown territory.
According to this RFC document: Domain Name System (DNS) names are "case insensitive". That is stated right at the top of the document in the Abstract section.
Going by the RFC, Pingdom's DNS tool is incorrect in flagging the SOA records with differing letter cases as error. One can label the DNS management work at the registrar as sloppy or clumsy, but this discrepancy should at best only rise to a warning level.