Not sure what exactly are you asking about. iptables/nftables is an interface for in-kernel packet filters. NetworkManager... well, manages your interfaces and

Not sure what exactly are you asking about. iptables/nftables is an interface for in-kernel packet filters. NetworkManager... well, manages your interfaces and connections. systemd-resolved/dnsmasq handle DNS. They mostly just do their own thing, with NM sometimes using the other ones as needed (for example, it will set forwarding rules up and run dnsmasq when you choose a "Shared to other computers" option in NM).