Nameservers: the foundation of your online presence
Nameservers (NS) are the authoritative DNS servers for your domain: they contain the official DNS records and respond to queries from resolvers around the world. If your nameservers are down, your domain is unreachable — website, email, APIs, everything stops working. For this reason, the correct configuration and monitoring of nameservers are among the most critical aspects of domain management.
DNS delegation is the mechanism by which the TLD registry (e.g., .com, .it) tells resolvers which are the authoritative nameservers for your domain. This delegation is configured at the registrar where you purchased the domain. If the delegation is wrong (points to incorrect or no longer active nameservers), the domain is unresolvable. Our NS Lookup verifies both the nameservers delegated in the TLD and those declared in the DNS zone, identifying any discrepancies.
Nameserver best practices
Every domain must have at least 2 nameservers, but 3 or 4 are recommended for high availability. Nameservers should be on different networks (ideally different data centers) to withstand localized failures. Some critical domains use nameservers from different providers: for example ns1.cloudflare.com and ns2.google.com. This multi-provider strategy offers maximum resilience but requires synchronizing records between providers.
Regularly verify that all your nameservers respond and return the same answers. The DNS Health Check automates this verification, comparing responses from each NS and flagging inconsistencies. A nameserver that does not respond or returns different records from the others causes intermittent resolution problems, which are the hardest to diagnose because they depend on which NS is queried.
Common nameserver problems
Lame delegation is the most insidious NS problem: it occurs when a nameserver is listed as authoritative for a domain in the TLD but is not actually configured to respond. This typically happens after a hosting migration when the NS records are updated at the registrar but the zone is not configured on the new DNS provider, or vice versa. Lame delegation causes timeouts and intermittent resolution failures.
Another common problem is a mismatch between the NS records registered in the TLD and those declared in the DNS zone. The NS records in the zone should exactly match those registered at the registrar. After every DNS migration, verify with NS Lookup that the delegation in the TLD and the NS records in the zone are aligned. Propagation of NS changes in the TLD can take up to 48 hours, during which you may have a mixed configuration.
Finally, pay attention to glue records: if your nameservers are under the domain itself (ns1.example.com for example.com), the TLD needs glue records (A records registered directly in the TLD) to break the circular dependency. Without glue records, the resolver cannot resolve the nameserver because it would need to query the nameserver itself. Glue records are configured at the registrar and must be updated if the nameserver IPs change.