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6.3.2. Addressing Issues
| Issue | Symptom | Solution |
|---|---|---|
| Duplicate IP | Intermittent connectivity | Find and remove duplicate |
| DHCP exhaustion | New devices can't get addresses | Expand scope, reduce lease time |
| Incorrect gateway | Reach local, not remote | Fix gateway configuration |
| Wrong subnet mask | Partial connectivity | Correct the mask |
| APIPA address (169.254.x.x) | Can't reach DHCP | Check DHCP server, relay, connectivity; if only one client is affected, check that client's DHCP settings and network profile |
| DNS failure | Ping by IP works, by name fails | Check the client's DNS server settings; test with nslookup/dig |
⚠️ Exam Pattern: Duplicate IPs cause intermittent problems because traffic alternates between both devices as ARP tables update. If symptoms come and go unpredictably, check for duplicates.
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Written byAlvin Varughese
Founder•20 professional certifications