  We present a dual fault-tolerant distance oracle for undirected and
unweighted graphs. Given a set $F$ of two edges, as well as a source node $s$
and a destination node $t$, our oracle returns the length of the shortest path
from $s$ to $t$ that avoids $F$ in $O(1)$ time with a high probability. The
space complexity of our oracle is $\Tilde{O}(n^2)$ \footnote{$\Tilde{O}$ hides
poly$\log n$ factor }, making it nearly optimal in terms of both space and
query time. Prior to our work, Pettie and Duan [SODA 2009] designed a dual
fault-tolerant distance oracle that required $\Tilde{O}(n^2)$ space and $O(\log
n)$ query time. In addition to improving the query time, our oracle is much
simpler than the previous approach.
