Networks, Hardware, and IT Infrastructure for Office Environments
Networks, hardware, and IT infrastructure questions test whether you can specify and troubleshoot the office environment: addressing, switching, wireless, remote access, servers, storage, power, and availability.
Core rules
- TCP/IP addressing: private ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. A /26 subnet has 64 addresses, 62 usable hosts after network and broadcast.
- DHCP assigns addresses; DNS resolves names; NAT translates private addresses to a public address. A DHCP scope exhaustion looks like intermittent connectivity, not a DNS failure.
- VLANs segment broadcast domains and support policy, but they are not a security boundary by themselves; use ACLs and firewalls.
- RAID improves availability or performance, not backup. RAID 0 stripes with no redundancy; RAID 1 mirrors; RAID 5 tolerates one disk failure; RAID 6 tolerates two; RAID 10 mirrors and stripes.
- Protect availability with UPS, redundant power and links, monitoring, and tested restores.
Worked example
A branch is assigned 192.168.10.0/26. The mask is 255.255.255.192. Addresses run from 192.168.10.0 to 192.168.10.63; the network address is .0 and broadcast is .63, leaving .1 to .62 usable, or 62 hosts. If the office needs 70 hosts, /26 is too small; move to /25, which gives 126 usable hosts. The reasoning is to count usable hosts, not total addresses.
Traps
- Calling RAID a backup strategy; it cannot restore deleted or corrupted files.
- Confusing DNS with DHCP when users can reach IP addresses but not names.
- Assuming more bandwidth always fixes latency; latency and packet loss need separate diagnosis.
- Forgetting that a /26 has 62, not 64, usable hosts.