Preg_Match Assistance

I have a dns zone file that looks like this

;########AB#######
AB1501 IN A 192.168.0.1
AB1502 IN A 192.168.0.1
AB1502 IN A 192.168.0.1
AB1502 IN A 192.168.0.1

I want to be able to cut out just the AB1501, AB1502, etc... as the names will be inserted into a database.

I am using this preg_match command in a if statement

 
preg_match("ab/i", $data) 
$name = substr($data, 0, 4);

but my output also includes the ### line, so it looks like this

 
;### N
AB1501
AB1502
AB1503
;### N

I need to not include the ";### N" lines. How can I exclude them in my preg_match statement?

Any help would be greatly appreciated.

Thanks

Solved this by adding ^ for start off.

preg_match("^ab/i", $data) 

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