CCNA
793 incident response problems that help with CCNA prep.
먼저 읽을 가이드
추천 문제
All problems (793)
NETWORK-136DHCP snooping trust is correct in the running config, but stack renumbering loses it from the new uplink member after reloadClient onboarding fails only after a restart because the logical uplink identity changed under the stack.NetworkIntermediate16 minProNETWORK-120IPv4 default routing is stable, but RA guard blocks new IPv6 gateway updates and dual-stack clients degrade graduallyConnectivity seems mostly fine until IPv6 freshness matters, because the edge no longer permits router advertisements from the intended gateway.NetworkIntermediate16 minProNETWORK-112NTP stratum looks valid but symmetric peer mode creates a timing loop across the switch stackEvery device claims a trustworthy source, yet the stack drifts because peers are feeding each other instead of a real upstream reference.NetworkIntermediate16 minProNETWORK-131One switch in the ring has the wrong MST region name, and the topology becomes a boundary only after a reboot reloads the saved configThe live network was temporarily aligned, but the persisted spanning-tree identity says otherwise.NetworkIntermediate16 minProNETWORK-123Storm control on an uplink clamps ARP bursts during failover and clients intermittently lose gateway discoveryThe network remains mostly up, but protection tuning now interferes with a valid convergence burst.NetworkIntermediate16 minProNETWORK-145The DHCP server is reachable, but Option 82 formatting changed during a switch replacement and the server now classifies the circuit incorrectlyAddress assignment survives at layer 3, yet edge identity metadata no longer matches the server's policy rules.NetworkIntermediate16 minProNETWORK-288A campus access stack advertises the voice VLAN while the downstream trunk template still prunes it on the uplink during a failover rehearsalPhones discover the right segment and the wired path never carries it end to end. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.NetworkIntermediate17 minProNETWORK-240A DHCP snooping database is written locally while the standby supervisor never receives the binding state during a failover rehearsalThe live chassis knows the clients and failover starts from an empty trust picture. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.NetworkIntermediate17 minProNETWORK-300A DNS resolver cluster still answers while one firewall update blocks only the TCP fallback path for large DNSSEC-signed replies during a failover rehearsalMost lookups work and the larger signed ones expose the hidden protocol gap. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.NetworkIntermediate17 minProNETWORK-186A relay path reaches the DHCP server while circuit identity metadata no longer matches the edge that sends it during a failover rehearsalThe server is up and the server-side policy no longer classifies the circuit the way the access layer expects. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.NetworkIntermediate17 minProNETWORK-216Small DNS lookups work while large-response TCP fallback is still blocked during a failover rehearsalResolution seems mostly healthy until response size changes the protocol path. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.NetworkIntermediate17 minProNETWORK-168User traffic survives a VLAN translation while onboarding protocols never see the same identity during a failover rehearsalThe data plane looks healthy and the control plane for voice or discovery still breaks. Normal traffic masked the issue until the standby or alternate path became active under rehearsal conditions.NetworkIntermediate17 minProNETWORK-483A resolver answers from cache (DNS Resolution Failure)A resolver answers from cache (DNS Resolution Failure) focuses on Network Services And Operations and asks the reader to isolate DNS Resolution Failure. 실무에서는 dns-resolution-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate18 minProNETWORK-467A VLAN handoff trunks correctly (Auth and Session Failure)A VLAN handoff trunks correctly (Auth and Session Failure) focuses on Switching And Vlan Design and asks the reader to isolate Auth and Session Failure in Cisco. 실무에서는 auth-and-session-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate18 minProNETWORK-471A VLAN handoff trunks correctly (Auth and Session Failure)A VLAN handoff trunks correctly (Auth and Session Failure) focuses on Switching And Vlan Design and asks the reader to isolate Auth and Session Failure in Cisco. 실무에서는 auth-and-session-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate18 minProNETWORK-480A resolver answers from cache (DNS Resolution Failure)A resolver answers from cache (DNS Resolution Failure) focuses on Network Services And Operations and asks the reader to isolate DNS Resolution Failure. 실무에서는 dns-resolution-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate19 minProNETWORK-018A proxy keepalive setting difference makes latency spike for only certain APIsA situation where, on the same server, only some paths are unusually slow because of a difference in upstream connection reuse policy.NetworkIntermediate20 minProNETWORK-542A resolver answers from cache (DNS Resolution Failure)A resolver answers from cache (DNS Resolution Failure) focuses on Network Services And Operations and asks the reader to isolate DNS Resolution Failure. 실무에서는 dns-resolution-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate20 minProNETWORK-599A resolver answers from cache (DNS Resolution Failure)A resolver answers from cache (DNS Resolution Failure) focuses on Network Services And Operations and asks the reader to isolate DNS Resolution Failure. 실무에서는 dns-resolution-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate20 minProNETWORK-530A VLAN handoff trunks correctly (Auth and Session Failure)A VLAN handoff trunks correctly (Auth and Session Failure) focuses on Switching And Vlan Design and asks the reader to isolate Auth and Session Failure in Cisco. 실무에서는 auth-and-session-failure 이슈를 볼 때 DNS, 라우팅, ACL/방화벽, 목적지 응답을 계층별로 잘라서 확인하면 장애 구간을 훨씬 빠르게 좁힐 수 있습니다.NetworkIntermediate20 minPro