$ORIGIN	.
$TTL	1

; OK
@	0		NS	@	; Minimal ttl
@	3600		NS	@	; Inner value
@	4294967295	NS	@	; Maximal ttl
@	1S		NS	@	; 1 second (upper-case)
@	1s		NS	@	; 1 second (lower-case)
@	1M		NS	@	; 1 minute (upper-case)
@	1m		NS	@	; 1 minute (lower-case)
@	1H		NS	@	; 1 hour (upper-case)
@	1h		NS	@	; 1 hour (lower-case)
@	1D		NS	@	; 1 day (upper-case)
@	1d		NS	@	; 1 day (lower-case)
@	1W		NS	@	; 1 week (upper-case)
@	1w		NS	@	; 1 week (lower-case)
@	1w1d1h1m1s	NS	@	; More time units
@	1s1m1m		NS	@	; Same time units, non decreasing order

; KO
@	-1		NS	@	; Negative ttl
@	4294967296	NS	@	; 32bit overflow
@	100000000W	NS	@	; 32bit overflow
@	4294967295s1w	NS	@	; 32bit overflow
@	1x		NS	@	; Unknown time unit