Q: A production server requires high network availability. You have two physical NICs and need to configure network bonding (NIC teaming) for redundancy. Explain the bonding modes and which one you'd choose for a production database server.

Linux network bonding combines multiple physical NICs into a single logical interface for redundancy and/or throughput.

• Mode 0 (balance-rr): Round-robin — packets are distributed across NICs sequentially. Increases throughput but requires switch configuration (EtherChannel/LACP).
• Mode 1 (active-backup): Only one NIC is active; the standby takes over if the active fails. No switch configuration needed. Best for database servers where reliability matters more than throughput.
• Mode 2 (balance-xor): XOR-based distribution. Requires switch support.

Common bonding modes: For a production database server, Mode 1 (active-backup) is the safest choice: The miimon=100 parameter checks link health every 100ms for fast failover.

nmcli con add type bond con-name bond0 ifname bond0 bond.options "mode=active-backup,miimon=100"
nmcli con add type ethernet con-name bond0-slave1 ifname eth0 master bond0
nmcli con add type ethernet con-name bond0-slave2 ifname eth1 master bond0

• Mode 4 (802.3ad / LACP): Dynamic link aggregation using the IEEE standard. Provides both redundancy and increased throughput. Requires switch LACP support.
• Mode 6 (balance-alb): Adaptive load balancing. No switch configuration needed, balances outgoing traffic.