Question re: domain NS records

[Mike Voss]

Question:  I have about 200 domains using the 3 nameservers I run in
my domain in their NIC records for SOA. 

If I want to change the IP of one of my nameservers, when I update it
in my domain, will it automatically be picked up by all domains using
it, or would each domain have to be individually modified ?  I know
when you register a domain you have to enter both name and IP for each
nameserver, so I'm wondering if either gets dynamically updated or if
they are forever static in the record until modified.

Many thanks,

Mike