To determine if two hosts can communicate directly, their IP addresses must:
* Belong to the same subnet
* Have matching subnet boundaries (based on their masks)
Let's evaluate each:
A: 192.168.17.15/29 # Subnet: 192.168.17.8 - 192.168.17.15
192.168.17.20/28 # Subnet: 192.168.17.16 - 192.168.17.31
# Different subnets ##
B: 10.5.5.1/24 # Subnet: 10.5.5.0 - 10.5.5.255
10.5.5.100/25 # Subnet: 10.5.5.0 - 10.5.5.127
# Different masks # Host with /25 may treat others outside /25 as unreachable ## C: 10.10.0.17/22 # Range: 10.10.0.0 - 10.10.3.255
10.10.1.30/23 # Range: 10.10.0.0 - 10.10.1.255
# Both addresses fall within same larger /22 range ##
D: 192.168.0.5/26 # Subnet: 192.168.0.0 - 192.168.0.63
192.168.0.100 # Not enough info; assume default /24
# /26 and /24 will not overlap fully # likely unreachable ##
MTCNA Course Manual - IP Subnetting:
"Hosts can communicate directly if they are in the same IP range and have the same subnet mask. Different subnet boundaries require routing." Rene Meneses Guide - Mask Comparison:
"Be cautious of overlapping address ranges. Matching IPs in same range with differing subnet masks may fail to communicate." Terry Combs Notes - Direct Connectivity Rules:
"Same subnet mask and same address block = direct communication. If masks differ, communication needs a router."