Srini, ASA5510 counts with 5 10/100Base-T physical ports, if you brake these down you will have.

1- One outside interface

2- One Inside interface

3- One Management interface

4- Two 10/100 any purpose interfaces

If using Base lisence this model can support 50 VLANs ( Virtual interfaces) in other words logical interfaces. This means for example say you you need 50 DMZs you will need to use 802.1q trunking from a single physical port to comeup with 50 logical interfaces, or you could use two physical ports using 25 VLANS per two physical ports.

If using Security Plus Lisence the ASA5510 can support a total of 100 VLANs (Logical interfaces and you can use the same principle example above, please refer to link bellow for more detailed information.

ASA5500 Model Comparison

http://www.cisco.com/en/US/products/ps6120/prod_models_comparison.html

Rgds

Jorge