dnscontrol/documentation/functions/domain/NAMESERVER_TTL.md

name	parameters	parameter_types
NAMESERVER_TTL	ttl	ttl target modifiers... Duration string RecordModifier[]

NAMESERVER_TTL sets the TTL on the domain apex NS RRs defined by NAMESERVER.

The value can be an integer or a string. See TTL for examples.

D('example.com', REGISTRAR, DnsProvider('R53'),
  NAMESERVER_TTL('2d'),
  NAMESERVER('ns')
);

Use NAMESERVER_TTL('3600'), or NAMESERVER_TTL('1h'), for a 1h default TTL for all subsequent NS entries:

D('example.com', REGISTRAR, DnsProvider('xyz'),
  DefaultTTL("4h"),
  NAMESERVER_TTL('3600'),
  NAMESERVER('ns1.provider.com.'), //inherits NAMESERVER_TTL
  NAMESERVER('ns2.provider.com.'), //inherits NAMESERVER_TTL
  A('@','1.2.3.4'), // inherits DefaultTTL
  A('foo', '2.3.4.5', TTL(600)) // overrides DefaultTTL for this record only
);

To apply a default TTL to all other record types, see DefaultTTL