Network Operations Journal Practice Flashcards

Flashcards covering NOC operations, network troubleshooting fundamentals, RouterOS configuration, and fault isolation principles.

What is the core principle regarding evidence versus assumptions in NOC operations?

Rely on evidence which can be collected to make decisions, not on what anyone says—evidence over assumptions at all times.

What is the typical packet loss percentage in dense structures such as basements or reinforced concrete, and how is it evaluated for LTE services?

Packet loss is often >5%, which is considered unusable for LTE services.

What are the three reserved number ranges that identify private IP addresses?

192.168.0.0 – 192.168.255.255, 10.0.0.0 – 10.255.255.255, and 172.16.0.0 – 172.31.255.255.

What should be done first when a customer experiences loss of connectivity but optical levels are within specification and the OLT confirms the MAC address is learned correctly?

Rebuild the WAN session using the least disruptive method available (restarting the WAN interface remotely or power-cycling the router for 30–60 seconds) before requesting ONT reprovisioning or FNO escalation.

Why should a MikroTik bridge be set to auto-mac=no with the admin MAC locked to a static physical interface address like ether2?

To prevent MAC address dynamic changes when physical interfaces flap or unplug, which flushes switch Layer-2 MAC address tables (CAM tables), resets ARP tables, drops WinBox sessions, and triggers STP topology changes.

Which static, non-overlapping channels should be locked when configuring 2.4 GHz Wi-Fi to avoid interference?

Channels 1 (2412 MHz), 6 (2437 MHz), and 11 (2462 MHz).

How is an FNO NNI mapping failure conclusively identified when a client router displays repeating PADO timeouts?

Optical light levels are healthy (typically -19 dBm to -22 dBm) and the FNO access node confirms the CPE MAC is learned on their internal access VLAN, but the PacketSky Core BNG interface displays zero learned MACs on the assigned S-VLAN.

What three questions must every quality escalation answer according to NOC Support Principle 13?

What is happening? What evidence supports it? What has already been ruled out?

What does a flat, symmetrical speed test ceiling immediately following a speed upgrade indicate?

An access provisioning layer profile mismatch on the FNO's OLT, where the updated bandwidth profile has not been correctly applied.

Why is TCP MSS Clamping required on PPPoE connections, and how is it implemented in RouterOS?

PPPoE header encapsulation adds an 8-byte overhead to standard 1500-byte MTU (reducing MTU to 1492 bytes); it is implemented in /ip firewall mangle using action=change-mss with new-mss=clamp-to-pmtu for TCP SYN packets.

Why does disabling SIP ALG have zero effect on Zoom, Microsoft Teams, or Google Meet call drops?

Zoom, Teams, and Google Meet do not use the SIP protocol (Port 5060/5061); they operate over proprietary UDP/TCP media streams, meaning call drops are caused by L2/L3 packet loss, Wi-Fi interference, or backhaul MTU bottlenecks.

What is the function of the forward chain firewall filter rule drop connection-nat-state=!dstnat in-interface-list=INTERNET?

It drops unsolicited incoming traffic from the INTERNET interface list unless the connection matches an active Destination NAT (Port Forwarding) rule.