Awk processing and parsing - parsing

Question

Trying to use STRICTLY awk to solve a little issue and I can't wrap myself around the solution:
# more connections
0x828ac008 127.0.0.1:5152 127.0.0.1:1387 2000
0x82cc28f8 10.4.4.63:1435 10.4.4.72:22 1132
0x82ec1de0 10.4.4.63:1524 50.28.90.36:8080 3248
# awk -F":" '/[0-9]/{print $1,$2}' connections | awk '!/^127/{print "nslookup "$4}'
nslookup 127.0.0.1
nslookup 10.4.4.72
nslookup 50.28.90.36
I am looking for a streamlined method to just parse out anything aside from loopbacks ^127 and the 10. addresses in my netblock. Yes, I know I can use sed, grep, cut, etc, but I'm hoping to see how someone else would do this in awk. Its more of a learning curve/a-ha! thing
Clarifying: Output would omit 10.x.x.x and 127.x.x.x
Output would be
nslookup 50.28.90.36
I tried awk !/^127\.|^10\./ but I couldn't get it to ignore the values.

Answer 1

This awk should work:
awk -F "[: ]+" 'NR>1 && !($4 ~ /^(127|10)\./){print "nslookup", $4}' connections
OUTPUT:
nslookup 50.28.90.36

Answer 2

Anubhava offers a great solution by setting Field Separators. Here is an alternate way of doing it using the default FS:
Using split function:
awk '$3!~/^(127|10)/{split($3,ip,/:/);print "nslookup",ip[1]}' connections
Using sub function:
awk '$3!~/^(127|10)/{sub(/:.*/,"",$3);print "nslookup", $3}' connections
Also a bash way of doing it:
while read -ra lines; do
[[ ! ${lines[2]} =~ "^(127|10).*" ]] && echo "nslookup ${lines[2]%:*}";
done < connections