i am a fan of Israel.could somebody tell me about their second strike capability.how do they retort if somebody(say Iran) strikes them first?certainly,the small size of israel must be a disadvantage.Iran seems to be developing a formidable strike capability.
I take it you're talking Nuclear weapons here?
Iran has nothing either now or in prospect that is capable of taking out the Israeli silo-mounted Jericho missiles which are assumed to provide the major proportion of their deterrent. That requires highly accurate missiles with sizeable nuclear warheads - both of which Iran does not have, and is not likely to get.
Moving on, the Israelis almost certainly have some form of air-launched nuclear weapon, gravity bombs at the very least. It would take a sizeable nuclear strike to take out all the air bases capable of launching such a strike. That is probably techinically within Iran's capability inside the next decade, but there is no way they could produce sufficient nuclear material within that time.
Finally, there are the Israeli Dolphin class subs which are reputedly capable of launching nuclear armed cruise missiles. The Israeli navy are awful, but are still by quite a margin the best in the Middle East. The best the Iranians can do there is take out as many of these as they can by destroying their home port (Haifa?) and accept that there is nothing they can do about the ones at sea.

I strongly recommend reading the "The Nuclear Game" series of essays, which can be found at the links below. They are extremely helpful in giving you an idea of what nuclear weapons can and cannot do - and will give you a far better idea for just how pathetic the Iranian strike capability against Israel is.

One - Two - Three
"I wish to heaven the Iron Curtain was windproof" - Unknown British Soldier, Korea