NETWORKING TIPS

250 is a lot to scroll through, so I’ll give you 250 networking tips grouped into bite-size sections. Use it as a checklist or reference you can dip into.

1. IP Addressing & Subnetting - 25 tips
1. Know the private ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
2. Memorize CIDR to subnet mask conversions for /24 to /30
3. Use /30 for point-to-point links to save IPs
4. Always reserve .1 or .254 for gateways in a subnet
5. Understand VLSM to avoid wasting addresses
6. Check for IP conflicts before assigning static IPs
7. Use DHCP for end devices, static for servers/printers
8. Document every static IP assignment
9. Avoid using .0 and .255 as host addresses
10. Know how to calculate network/broadcast addresses fast
11. Use IPv6 link-local addresses for troubleshooting
12. Keep /64 for IPv6 subnets - don’t subnet smaller
13. Avoid overlapping subnets in your network design
14. Use loopback IPs for router testing and stability
15. Understand NAT and PAT differences
16. Use NAT overload for home/small office internet
17. Check subnet mask matches on all devices in a LAN
18. Use secondary IPs for multi-subnet on one interface
19. Plan for growth - don’t use the entire subnet on day 1
20. Know how to find the number of hosts: 2^h - 2
21. Use supernetting to summarize routes
22. Avoid mixing public and private IPs on same LAN
23. Test connectivity with ping and traceroute after IP changes
24. Use ARP to check IP-MAC mappings
25. Keep a subnetting cheat sheet handy

2. Routing & Switching - 30 tips
26. Understand default gateway purpose
27. Use static routes for simple networks
28. Use OSPF or EIGRP for dynamic routing in mid-size nets
29. Set router ID explicitly to avoid issues
30. Use passive-interface for LANs in OSPF
31. Redistribute routes carefully to avoid loops
32. Use route summarization to reduce routing table size
33. Check routing table with `show ip route`
34. Understand administrative distance values
35. Use floating static routes for backup paths
36. Enable VLANs to segment broadcast domains
37. Use trunk ports only between switches/routers
38. Set native VLAN and don’t use VLAN 1 for traffic
39. Enable spanning tree and use Rapid PVST+
40. Set root bridge manually for predictable topology
41. Use portfast on access ports, never on trunks
42. Use BPDU Guard to prevent rogue switches
43. Check MAC address table for troubleshooting
44. Use link aggregation for bandwidth and redundancy
45. Understand L2 vs L3 switches
46. Use SVI for inter-VLAN routing on L3 switches
47. Avoid STP loops by planning physical topology
48. Use HSRP/VRRP for gateway redundancy
49. Set priority values to control active router
50. Use QoS to prioritize voice/video traffic
51. Understand MPLS basics for ISP networks
52. Use ACLs to control traffic directionally
53. Place extended ACLs close to source
54. Place standard ACLs close to destination
55. Test ACLs with permit/deny logs

3. Troubleshooting - 30 tips
56. Check physical layer first - cables, LEDs, power
57. Use `show interfaces` for errors and drops
58. Clear counters before testing to get clean data
59. Use ping with different packet sizes
60. Use traceroute to find where traffic stops
61. Check ARP table for missing mappings
62. Verify DNS resolution separately from IP connectivity
63. Use `nslookup` or `dig` for DNS tests
64. Check duplex/speed mismatches on interfaces
65. Avoid auto-negotiation issues by setting manually
66. Look for MTU mismatches causing fragmentation
67. Use packet capture with Wireshark for deep analysis
68. Check firewall rules when traffic is blocked
69. Verify VLAN assignment on ports
70. Check for DHCP scope exhaustion
71. Use DHCP snooping to prevent rogue servers
72. Check CPU/memory on devices under load
73. Look at logs - `show log`, syslog
74. Reboot as last resort, not first
75. Isolate the problem by testing layer by layer
76. Use loopback testing to isolate hardware faults
77. Check routing loops with TTL exceeded errors
78. Verify ACL hit counts to see if it’s matching
79. Use debug commands sparingly and off-hours
80. Document changes before and after troubleshooting
81. Use network diagrams to visualize paths
82. Check for asymmetric routing issues
83. Verify NAT translations with `show ip nat translations`
84. Test from multiple sources to rule out client issues
85. Keep a lab for reproducing problems safely

4. Security - 30 tips
86. Change default passwords immediately
87. Use strong, unique passwords or SSH keys
88. Disable unused interfaces and services
89. Use SSH instead of Telnet
90. Enable login banners with legal warnings
91. Use role-based access control on devices
92. Set exec-timeout on VTY lines
93. Use ACLs to restrict management access
94. Enable port security on access ports
95. Set maximum MAC addresses per port
96. Use DHCP snooping to prevent MITM
97. Use DAI to prevent ARP spoofing
98. Enable IP Source Guard
99. Keep firmware updated
100. Disable CDP/LLDP on edge ports
101. Use encrypted protocols - HTTPS, SFTP, SNMPv3
102. Segment guest and corporate networks
103. Use VLANs for separation
104. Implement 802.1X for port authentication
105. Monitor logs for failed login attempts
106. Use IDS/IPS for threat detection
107. Block unused ports at firewall
108. Use stateful inspection firewalls
109. Backup configs before changes
110. Store backups offsite/encrypted
111. Use NTP for accurate timestamps
112. Restrict SNMP community strings
113. Disable IP directed broadcasts
114. Use control plane policing
115. Regularly audit user accounts

5. Wireless Networking - 25 tips
116. Use 5GHz/6GHz for less congestion than 2.4GHz
117. Choose non-overlapping channels: 1, 6, 11 for 2.4GHz
118. Set channel width to 20MHz in crowded areas
119. Use WPA3 for best security
120. Avoid WEP and WPA1
121. Use separate SSIDs for guest and internal
122. Enable client isolation on guest networks
123. Place APs for coverage, not maximum power
124. Use site survey tools for placement
125. Avoid channel overlap with neighboring APs
126. Use band steering to push clients to 5GHz
127. Set minimum data rate to drop slow clients
128. Enable PMF for management frame protection
129. Use RADIUS for enterprise auth
130. Regularly update AP firmware
131. Monitor for rogue APs
132. Use directional antennas for point-to-point links
133. Check signal strength and SNR, not just RSSI
134. Avoid placing APs near microwaves/metal
135. Use QoS for voice/video over WiFi
136. Limit number of clients per AP
137. Enable fast roaming for mobile devices
138. Use DFS channels carefully due to radar
139. Document SSID, PSK, VLAN mapping
140. Test handoff between APs

6. Performance & Optimization - 25 tips
141. Monitor bandwidth usage with NetFlow/sFlow
142. Identify top talkers and protocols
143. Use QoS policies for critical apps
144. Prioritize VoIP with EF PHB
145. Limit P2P and streaming traffic if needed
146. Use traffic shaping to smooth bursts
147. Check for bufferbloat on WAN links
148. Use TCP window scaling for long-distance links
149. Enable jumbo frames where supported end-to-end
150. Reduce broadcast traffic with VLANs
151. Use multicast for one-to-many streaming
152. Tune ARP timeout values
153. Use caching DNS servers locally
154. Offload SSL/TLS where appropriate
155. Use CDN for static content
156. Check for asymmetric paths causing retransmits
157. Tune TCP MSS to avoid fragmentation
158. Use link aggregation for redundancy and throughput
159. Monitor latency and jitter for VoIP
160. Use SD-WAN for WAN optimization
161. Avoid overloading single links
162. Use ECMP for load balancing
163. Set appropriate queue depths
164. Monitor interface errors and discard packets
165. Keep firmware updated for performance fixes

7. Best Practices & Design - 25 tips
166. Document everything - diagrams, IPs, configs
167. Use consistent naming conventions
168. Label cables and ports physically
169. Keep network diagrams updated
170. Use change control process
171. Test changes in lab first
172. Plan for scalability from start
173. Use hierarchical design: core, distribution, access
174. Avoid single points of failure
175. Use redundant links and devices
176. Keep management network separate
177. Use out-of-band management where possible
178. Standardize configs across devices
179. Use templates for deployment
180. Automate repetitive tasks with Ansible/Python
181. Version control your configs
182. Use monitoring tools - Zabbix, PRTG, LibreNMS
183. Set up alerts for critical events
184. Keep spare hardware on hand
185. Plan IP space for 3-5 years growth
186. Use DHCP reservations for critical devices
187. Keep firmware/software inventory
188. Review configs quarterly
189. Train staff on network basics
190. Have an incident response plan

8. IPv6 - 20 tips
191. Enable IPv6 on dual-stack networks
192. Use SLAAC for stateless config
193. Use DHCPv6 for stateful config
194. Understand IPv6 address types: global, link-local, ULA
195. Don’t use NAT in IPv6
196. Use firewall rules for security
197. Check RA guard to prevent rogue routers
198. Use IPv6 ACLs separately from IPv4
199. Test IPv6 connectivity with ping6
200. Understand IPv6 subnetting /64 boundaries
201. Use IPv6 for IoT devices
202. Monitor IPv6 neighbor cache
203. Use IPv6 over VPN tunnels
204. Disable IPv6 if not used to reduce attack surface
205. Plan IPv6 addressing scheme early
206. Use DNS AAAA records
207. Test applications for IPv6 compatibility
208. Use IPv6 transition mechanisms: 6to4, Teredo, NAT64
209. Monitor IPv6 traffic separately
210. Keep up with IPv6 best practices from RIPE/ARIN

9. VPN & Remote Access - 20 tips
211. Use IPsec for site-to-site VPNs
212. Use SSL/TLS VPN for remote users
213. Use strong encryption: AES-256, SHA-256
214. Use certificate-based auth where possible
215. Limit VPN access by group/role
216. Enable split tunneling carefully
217. Monitor VPN logs for anomalies
218. Use MFA for VPN logins
219. Set idle timeouts on VPN sessions
220. Use DPD for tunnel keepalive
221. Test failover between VPN tunnels
222. Document VPN endpoints and peers
223. Use dedicated VPN devices for performance
224. Check MTU for VPN overhead
225. Avoid overlapping subnets across sites
226. Use BGP over IPsec for dynamic routing
227. Limit access once inside VPN
228. Use Zero Trust principles
229. Log all VPN connections
230. Regularly rotate VPN keys/certs

10. Cloud & Modern Networking - 20 tips
231. Understand VPC/VNet concepts
232. Use security groups and NSGs for firewalls
233. Use private subnets for backend resources
234. Use NAT Gateway for outbound internet
235. Use peering/VPN for hybrid connectivity
236. Monitor cloud network costs
237. Use auto-scaling with load balancers
238. Understand cloud DNS services
239. Use Infrastructure as Code for networking
240. Tag resources for tracking
241. Use flow logs for troubleshooting
242. Understand shared responsibility model
243. Use SD-WAN for multi-cloud connectivity
244. Test latency to cloud regions
245. Use private endpoints for services
246. Avoid public IPs on internal resources
247. Use CloudFront/Azure CDN for edge
248. Monitor API gateway traffic
249. Use microsegmentation in containers
250. Keep learning - networking changes fast

Want me to turn this into a printable PDF or focus on just one area like troubleshooting or security with 50 deeper tips?