Check for dangling DNS in a list of CNAMES and their target record

dns-check.sh

#!/usr/bin/env bash
# FILE is a csv dumped from some source, i.e. Azure. Columns formatted like: "DnsRecord","Record","RecordType"
FILE="AllAzureDnsRecords10-08-2021-16.csv"
NEWFILE="dangling_records.csv"
DEADDNS=()
for line in $(grep "CNAME" ${FILE}); do 
    TARGET=$(echo ${line} | cut -d, -f2 | sed s/\"//g)
    CNAME=$(echo ${line} | cut -d, -f1 | sed s/\"//g)
    echo "Checking ${TARGET}..."
    RESPONSE=$(host ${TARGET})
    RESULT=$?
    if [[ ${RESPONSE} == *"not found"* ]]; then
        DEADDNS+=(${CNAME}","${TARGET})
        echo ${RESPONSE}
    elif [ ${RESULT} == 1 ]; then
        DEADDNS+=(${CNAME}",NULL")
    fi
done

echo "CNAME,DEADEND" > ${NEWFILE}
for i in ${DEADDNS[@]}; do
    echo ${i} >> ${NEWFILE}
done