Let
G
be a graph. Denote by
d
u
, the degree of a vertex
u
of
G
and represent by
v
w
, the edge of
G
with the end-vertices
v
and
w
. The sum of the quantities
d
u
2
+
d
v
2
d
u
−
1
d
u
−
1
over all edges
u
v
of
G
is known as the symmetric division deg (SDD) index of
G
. A connected graph with
n
vertices and
n
−
1
+
k
edges is known as a (connected)
k
-cyclic graph. One of the results proved in this study is that the graph possessing the largest SDD index over the class of all connected
k
-cyclic graphs of a fixed order
n
must have the maximum degree
n
−
1
. By utilizing this result, the graphs attaining the largest SDD index over the aforementioned class of graphs are determined for every
k
=
0,1
,
…
,
5
. Although, the deduced results, for
k
=
0,1,2
, are already known, however, they are proved here in a shorter and an alternative way. Also, the deduced results, for
k
=
3,4,5
, are new, and they provide answers to two open questions posed in the literature.