This is the rn (Relative Name), the single naming segment that, appended to its parent's dn, forms the full dn for this one instance of an IPv4 DNS server address configured for the management network, one of the name servers UCS Manager/CIMC will query to resolve hostnames. UCS Manager derives this segment automatically from the object's own defining attribute (such as an address, index, or configured name), so seeing a distinctive rn like this is how you tell one IPv4Dns row apart from every sibling row under the same parent. For this class the rn typically looks like 'ipv4-dns-10.1.1.53'.