#!/usr/bin/env bash

# Define the path to the resolv.conf file
resolv_conf="/etc/resolv.conf"

# Display the current nameserver entry
current_dns_server=$(grep '^nameserver' "$resolv_conf" | awk '{print $2}')
echo "Current DNS server: $current_dns_server"

# Prompt the user for DNS server input or use default
read -p "Enter new DNS server IP (default is 1.1.1.1): " dns_server
dns_server=${dns_server:-1.1.1.1}

# Check if the provided DNS server resolves correctly
if nslookup bigbeartechworld.com "$dns_server" &> /dev/null; then
    echo "$dns_server can resolve correctly."
else
    echo "$dns_server cannot resolve. Exiting without making changes."
    exit 1
fi

# Backup the original resolv.conf file
cp "$resolv_conf" "$resolv_conf.bak"

# Replace nameserver entries with the user-provided or default DNS server
sed -i "s/nameserver.*/nameserver $dns_server/" "$resolv_conf"

# Display the updated resolv.conf
echo "Updated /etc/resolv.conf:"
cat "$resolv_conf"