$ORIGIN	.

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

; KO
$TTL	-1		; Negative ttl