Simple "One-liner" DNS-timing

dns-timing.sh

#!/usr/bin/env bash

# set -x

##
## DNS timing "one-liner"
##

function _dns_timing() {
    local EMAIL='[email protected]'
    local HOSTS=( 'www.google.com' 'www.aol.com' 'www.reddit.com' 'netdna.bootstrapcdn.com' )
    curl -s -o test-hosts.sh 'https://gist.githubusercontent.com/smj10j/b72547d71f06e8a242ff43ee683b4e71/raw/test-hosts.sh'
    echo "==================================================" >> test-hosts.log
    echo "============== $(date) ==============" >> test-hosts.log
    bash test-hosts.sh "${HOSTS[@]}" 2>&1 | tee -a test-hosts.log
    echo "==================================================" >> test-hosts.log
    mail -s "DNS timing results from $(curl ifconfig.me) via $(whoami)@$(hostname)" ${EMAIL} < test-hosts.log
}
export _dns_timing
_dns_timing

test-hosts.sh

#!/bin/bash
#set -x

declare -a HOSTS
declare -a TTLS
declare -a TTL_SUMS
HOSTS=("$@")
TTLS=( )
TTL_SUMS=( 0 0 )
N=50
NUM_HOSTS=${#HOSTS[@]}



function ttl() {
    #echo "$(host -r -a -t a $1)" | awk '/^'$1'/ {print $2}' | head -1
    echo "$(host -a -t a $1)" | awk '/^'$1'/ {print $2}' | head -1
}

function cleanup() {

#     echo ""
#     echo "TTLs:"
#     echo "${TTLS[@]}"
#     echo "TTL_SUMs:"
#     echo "${TTL_SUMS[@]}"
#     echo "HOSTs:"
#     echo "${HOSTS[@]}"

    echo ""
    LEN=$((${#TTLS[@]} / NUM_HOSTS))
    FS=$'\t'
    INDEX=0;
    echo "HOST${FS}TTL SUM${FS}NUM SAMPLES${FS}TTL AVG"
    for host in ${HOSTS[@]}; do
        echo "${HOSTS[INDEX]}${FS}${TTL_SUMS[INDEX]}${FS}$LEN${FS}"$((${TTL_SUMS[INDEX]} / LEN))
        INDEX=$((INDEX+1))
    done
}
trap cleanup EXIT

ITERATIONS=$((N*NUM_HOSTS))
echo "Iterations: $ITERATIONS"
echo "Num Hosts: $NUM_HOSTS"

for i in $(seq $ITERATIONS); do

    INDEX=$((i%NUM_HOSTS))
    HOST=${HOSTS[INDEX]}

    DELAY=$(echo "$RANDOM*0.00005" | bc)
    echo "Sleeping for ${DELAY}s..."
    sleep $DELAY

    TTL=$(ttl $HOST)
    TTLS[$i]=$TTL
    TTL_SUMS[$INDEX]=$((${TTL_SUMS[INDEX]}+TTL))
    echo "TTL to resolve $HOST: $TTL"

done