The distance spectral radius of a connected graph is the largest eigenvalue of the distance matrix of the graph. It is interest to determine those graphs that uniquely minimize and/or  maximize the distance spectral radius over some families of graphs. We report a recent work to determine the unique graph that maximizes the distance spectral radius over all n-vertex cacti with exactly k cycles, where 0\le k\le (n-1)/2, settling a conjecture in [S.S. Bose, M. Nath, S. Paul, On the distance spectral radius of cacti, Linear Algebra Appl. 437 (2012) 2128–2141].

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