The term is new to me. So I have a few questions about it.

I've heard it mostly happens with DNS servers? How do you protect against it? How do you know if your servers can be used as a victim?

This is a configuration issue right?

my named conf file

include "/etc/rndc.key";

controls {
        inet 127.0.0.1 allow { localhost; } keys { "rndc-key"; };
};

options {
    /* make named use port 53 for the source of all queries, to allow
         * firewalls to block all ports except 53:
         */

    // query-source    port 53;

    /* We no longer enable this by default as the dns posion exploit
        has forced many providers to open up their firewalls a bit */

    // Put files that named is allowed to write in the data/ directory:
    directory                "/var/named"; // the default
    pid-file                 "/var/run/named/named.pid";
    dump-file                "data/cache_dump.db";
    statistics-file          "data/named_stats.txt";
   /* memstatistics-file     "data/named_mem_stats.txt"; */
    allow-transfer {"none";};
};

logging {
/*      If you want to enable debugging, eg. using the 'rndc trace' command,
 *      named will try to write the 'named.run' file in the $directory (/var/named").
 *      By default, SELinux policy does not allow named to modify the /var/named" directory,
 *      so put the default debug log file in data/ :
 */
    channel default_debug {
            file "data/named.run";
            severity dynamic;
    };
};

view "localhost_resolver" {
/* This view sets up named to be a localhost resolver ( caching only nameserver ).
 * If all you want is a caching-only nameserver, then you need only define this view:
 */
    match-clients         { 127.0.0.0/24; };
    match-destinations    { localhost; };
    recursion yes;

    zone "." IN {
        type hint;
        file "/var/named/named.ca";
    };

    /* these are zones that contain definitions for all the localhost
     * names and addresses, as recommended in RFC1912 - these names should
     * ONLY be served to localhost clients:
     */
    include "/var/named/named.rfc1912.zones";
};

view "internal" {
/* This view will contain zones you want to serve only to "internal" clients
   that connect via your directly attached LAN interfaces - "localnets" .
 */
    match-clients        { localnets; };
    match-destinations    { localnets; };
    recursion yes;

    zone "." IN {
        type hint;
        file "/var/named/named.ca";
    };

    // include "/var/named/named.rfc1912.zones";
    // you should not serve your rfc1912 names to non-localhost clients.

    // These are your "authoritative" internal zones, and would probably
    // also be included in the "localhost_resolver" view above :