To find your IPv4 address:

$ dig -t a

To find your IPv6 address:

$ dig -t aaaa
IPv4 AddressIPv4 GatewayIPv6 AddressIPv6 Gateway

Checklist of networking topics to re-read:

Static NetworkingUpdate ifconfig, /etc/mygate, and /etc/hostname.if0
NSDUpdate the IPv6 addresses in nsd.conf and the zone file
ZNCUpdate the IPv6 addresses in znc.conf's listeners
ngircdUpdate the Listen = IP addresses in ngircd.conf
UnboundUpdate the outgoing-interface in unbound.conf
PingTroubleshoot networking using ping
NetcatTroubleshoot networking using netcat

Stale hostname

If you ever change your host's IP address, /etc/hosts may be intercepting the name lookup and giving you the old IP address.

Make sure there is no entry in the /etc/hosts files that is causing your machine to use the old IP.