* 10.1.32.0/19
* 10.1.64.0/19
* 10.1.96.0/19
You need to examine the third byte because that is the byte where the four prefixes differ: 0 = 0 0 0 0 0 0 0 0
* 32 = 0 0 1 0 0 0 0 0
* 64 = 0 1 0 0 0 0 0 0
* 96 = 0 1 1 0 0 0 0 0
The last 7 bits are irrelevant, so the mask is 1 0 0 0 0 0 0 0 and the EIGRP command is ip summary-address eigrp 1 10.1.0.0 255.255.128.0.
