Mentors Comment:
The answer is both traditional as well as current based. You have to provide the role of diplomacy in recent times which has averted international crisis by bringing peace in those situations.
Doklam crisis, summits between Korean leaders, Trump-Kim meet, diplomatic relations between US and Cuba, negotiations between Afghanistan govt and Taliban etc are some of the recent examples which you have to discuss.
At the same time, do give some examples of post WW2 diplomacy which helped in providing solutions to long time military crisis in the world.

To score better, provide a discussion on the challenges that diplomacy is facing in maintaining peace in this fast paced and ever changing relations between major players of the world.

Answer:
The world has transformed rapidly in the decade since the end of the Cold War. An old system is gone and, although it is easy to identify what has changed, it is not yet clear that a new system has taken its place. We are witnessing a rash of sometimes-violent expressions of claims to rights based on cultural identity, and a redefinition of sovereignty that imposes on states new responsibilities to their citizens and the world community. Amid growing tensions in the world forum, the role of military to defuse the tension has somehow taken a backseat and in recent time, more emphasis has been given to diplomacy.

Examples of recent diffusion of crisis through diplomacy:

Recently, Eritrea and Ethiopia ended their decade long war after the presidents of both countries met and signed the peace treaty. This was preceded by months of back channel diplomacy between the two war torn nations.
No one would have imagined that one day leaders of United States of America, South Korea and North Korea would cross the DMZ smiling. But this was made true with successful rounds of talks between the establishments of two nations and it eventually culminated in couple of summits between leaders of both nations. Tension in Korean peninsula seems to be on ease, thanks to the diplomacy.

The risk of a war between North Korea and the US was mounting steadily for the past year. But the situation was saved by the summits between President Trump and Kim.

There may be no clear winner here, but Doklam stands as a fine example of how to balance decisiveness with diplomacy. What was going to be an endless standoff between the Indian and Chinese army, was solved through backchannel diplomacy by both nation’s bureaucracy and strategic experts.

India Pakistan are witnessing their lowest ebb in bilateral relations after recent attacks on Indian military instalments by Pakistan based terror outfits and subsequent Pulwama attack and Balakot strike. The LOC has witnessed record ceasefire violations. But the real solution is being suggested through diplomacy. Its important to remember that the best years of relations between India and Pakistan are those when both nations held talks regularly and wanted to chalk out the issues through diplomacy.

US-Iran nuclear deal is an example of what diplomacy could have achieved which military interventions and economic sanctions failed to do in last 40 odd years. For the better part of 9 years, Iran along with permanent members of the UN Security Council and Germany sat and discussed the nuclear issue amicably. It resulted in the deal which now is facing stress after President Trump moved out of it.

After years of fighting with the Taliban, which saw Afghanistan turning into rubble, the USA has now initiated a talk with Taliban group and other powers like China and Russia have backed the diplomacy and are willing to sit together if it helps Afghanistan in securing peace.

Similarly world is replete with such incidents where diplomacy played a key role in diffusing tension. Be it Cuban missile crisis or Israel Egypt peace treaty of 1979; German reunification or US opening to China in 1972, all the major international efforts for peace have been concluded through diplomacy only.

Challenges for diplomacy:
Diplomacy, in this ear of chest thumping nationalism across the globe, has to conduct itself in a more time-sensitive manner, and be applied with a greater technical orientation.
Diplomacy today takes place among multiple sites of authority, power, and influence: mainly states, but also including religious organizations, NGOs, multinational corporations, and even individuals. It makes tracking the development and maintaining the required synergy to avert the crisis a difficult task.
The scenes in international politics are changing quite fast. All actors engaged in the world of diplomacy have to adjust their goals and actions to the fast emerging reality of the power shift from the Atlantic to Asia and the Pacific.
The foreign ministry and minister have lost influence to other government departments, to centralizing national leaders who assert direct control over affairs of state, and to international and non-governmental organizations.
Another potential difficulty is that the close involvement of heads of countries and their offices can mean that calculations of international politics override the demands of local government.

Today’s instantaneous communications should, in theory, make it easier to maintain international dialogue, to resolve differences and to promote understanding and cooperation. What is beyond doubt is that, in the absence of interaction by governments behind the scenes through vigorous diplomacy, things would be even worse than they already are and the world would be in permanent crisis.