I'm configuring a Cisco IOS (version 15) router, and I need to use the same values in multiple places; in this case, I need to configure the router's name servers (
ip name-server <address>) and also reference them in an ACL, as per this question (
permit udp <address> [...]). However, now I have the same IP address in two different places, and this could lead to confusion later, should f.e. the DNS servers change.
Is there any way to use some sort of variable for this? Does IOS even allow the use of variables?