Wie kann ich meine Nameserver im Unix-Stil prüfen?

#!/bin/sh

# yes, sh
# we're trying to be as much compatible as possible,
# trying to achieve POSIX/SUS compliance

# our main tool here:
query_cmd=host

status=0

# always lookup these hosts:
querylist_mandatory="peter.example.local jackson.example.local"

# name servers:
hostlist="10.32.1.5 10.32.254.250"

# zone-inputfile:
zonefile="/usr/local/etc/namedb/working/input/example.com.zone.input"
zonefile_qty=3

status_text=""

# make zonefile_domain empty by default:
zonefile_domain=""

# do we have a zonefile at all?
if [ ! -f $zonefile ]; then
    status=1
    status_text="$status_text\nNo zonefile! Going on with local list..."
    querylist_zonefile=""
else
    # read zonefile, get all IN A hostnames, sort randomly and uniquely, display only n entries:
    querylist_zonefile=`<$zonefile grep "^[^@].*[ \t]*IN[ \t]*A" | sed -E 's/^([a-zA-Z0-9-]*)[ \t].*/\1/g' | sort -Ru | head -n $zonefile_qty`

    # attention, here we're pulling its domain name from the zone input file
    # looking for ANY line with a ";ORIGIN" ANYWHERE on it:
    zonefile_domain=`<$zonefile grep ";ORIGIN " | sed -E 's/;ORIGIN[ \t]*([a-zA-Z0-9.]*)\.$/\1/g'`
fi

# let's use FQDNs if possible:
qlzf=""
if [ "$zonefile_domain" != "" ]; then
    for z in $querylist_zonefile; do
        qlzf="$qlzf $z.$zonefile_domain"
    done
fi

# sort our new list again:
querylist=`echo $qlzf $querylist_mandatory | sed 's/ /\n/g' | sort --ignore-case`

status_text="$status_text\n$querylist"

# looking up all that we've just prepared:
for q in $querylist; do
    for h in $hostlist; do
        cmd="$query_cmd $q $h"
        # status_text="$status_text\n$cmd"
        r=`$cmd`
        if [ $? -ne 0 ]; then
            status=2
            status_text="$status_text\n$cmd : $r"
        fi
    done
done

if [ $status -eq 0 ]; then
    # depending on how you notify via cron:
    # echo Successful.
else
    # again, depending how you're handling that, there are so many ways,
    # you could also mail from cron with a dedicated subject line etc,
    # here we're writing to stderr...
    echo "$zonefile_domain NS: FAILED! Status: $status" >&2
    echo $status_text | sed 's/\\n/\n/g' >&2
    echo >&2
fi

# ... and we're always returning with some exit code
# anything than zero will indicate an error:
exit $status