DNS performance is further affected by the presence of a large number of broken (lame) or inconsistent delegations. In our survey, address resolution failed for about 1.1% of nameservers due to timeouts or non-existent records, mostly stemming from spelling errors. For 14% of domains, authoritative nameservers returned inconsistent responses; a few authoritative nameservers reported that the domain does not exist, while others provided valid records. Failures stemming from lame delegations and timeouts can translate into significant delays for the end-user. Since these failures and inconsistencies largely stem from human errors , it is clear that manual configuration and administration of such a large scale system is expensive and leads to a fragile structure.