How to check if two CNAMEs point to the same IP address?

Question

I have two CNAMEs and want to verify if they point to the same IP. What is the best way to do it?

Input file:

cname1 cname2
cname3 cname4
...

Here is the code I have written:

#!/bin/bash
while read -r cname1 cname2; do
  ip1=$(dig +short "$cname1" | tail -1)
  ip2=$(dig +short "$cname2" | tail -1)
  [[ $ip1 != $ip2 ]] && printf '%s\n' "$cname1 and $cname2 differ: $ip1 $ip2"
done < cnames.txt

Is there a more efficient and robust way to do this?