IDC knowledge base
Practical guides to data center management, bandwidth billing, remote operations and IDC billing systems.
- Server operations
RAID 0 vs 1 vs 5 vs 10: one comparison table, then choose by workload
RAID 0 vs 1 vs 5 vs 10 differs in how data is made redundant. RAID 0 only stripes; RAID 1 mirrors two drives; RAID 5 spends one drive on parity, cheap per TB but slow on small writes and rebuilds; RAID 10 mirrors then stripes for steady random writes. Databases and VMs: RAID 10. Boot drives: RAID 1.
- Networking & IP
What is an IP address? Format, classes and how it works
An IP address is the number that identifies a network interface. IPv4 addresses are 32 bits written as four decimals, like 192.168.1.10: the network portion says which network, the host portion which device. Routers read the network portion; the MAC address handles the last hop.
- Server operations
1U vs 2U server: what actually differsand which one to buy
In a 1U vs 2U server comparison, CPU and memory are normally identical. The difference is what the extra 1.75 inches holds: 2–3 times the drive bays and PCIe slots, larger, quieter fans and higher-wattage power supplies, at the cost of a second rack unit. Web nodes go 1U; storage and GPU go 2U.
- Networking & IP
What is IPv6? Address structure, benefits and adoption
IPv6 is version 6 of the Internet Protocol and the successor to IPv4. It extends addresses from 32 to 128 bits, enough for every network segment to be a /64, and removes the need for layers of NAT. The catch: it cannot talk to IPv4 directly, so the two will coexist for years.
- Networking & IP
VLAN types: port, MAC, protocol and subnet-based membership compared
By how membership is assigned, there are four VLAN types: port-based, MAC-based, protocol-based and IP subnet-based. Port-based is set by the switch admin; the other three follow the device, so a host can change VLAN by changing its own MAC or IP. That is why data centers use port-based VLANs.
- Networking & IP
What is CIDR? Classless routing and slash notation explained
What is CIDR? Classless Inter-Domain Routing replaced Class A, B and C networks in 1993: the network part of an address is no longer fixed at 8, 16 or 24 bits but written after a slash. A /22 fixes the first 22 bits and leaves 10 free, a block of 1,024 addresses.
- Networking & IP
What is SNMP? How managers, agents and MIBs work together
SNMP (Simple Network Management Protocol) is an IETF protocol that monitoring systems use to read device status and devices use to send alerts. It has three parts: the manager that queries, the agent on the device, and the MIB that defines what can be read. Most networks run v2c or v3.
- Networking & IP
What is a VLAN? How one switch is split into separate broadcast domains
A VLAN (virtual LAN) groups switch ports under a number, and each group is its own broadcast domain: ports in one VLAN talk at Layer 2 as usual, while different VLANs cannot see each other. That number is the VLAN ID, 1 to 4094; on links shared by several VLANs, an 802.1Q tag carries it.
- Security & compliance
What is a DDoS attack? How it works, the three types and what you see when you are hit
What is a DDoS attack? A distributed denial of service attack makes many devices spread across the internet flood one target at once, exhausting its bandwidth, connections or CPU so real users cannot get in. It steals no data and breaks into nothing: it attacks availability.
- Server operations
How to enable PXE boot in BIOS: UEFI and legacy settings by server brand
To enable PXE boot in BIOS, turn on network boot for the NIC port (Network Stack or PXE Device in UEFI mode, the PXE option ROM in legacy mode), pick IPv4 or IPv6, and put the NIC in the boot order, or press F12 at POST to network boot once. Miss one and the NIC never appears.
- Networking & IP
How to find my IP address: local, private and public IP explained
How to find my IP address depends on which one you need. Your local IP sits on the network adapter: run ipconfig on Windows, ip addr on Linux or show ip interface brief on a switch. Your public IP is what internet servers see and can only be checked from outside. If they differ, NAT sits in between.
- Data center
PDU vs power strip: current, construction and safety
A rack PDU is the last stage of power distribution: it runs on a 16 A, 32 A or three-phase circuit, is fixed to the rack and can meter and switch outlets. A power strip is sized for one household outlet. A PDU can act as a power strip if the plugs fit; a strip does not belong in a server rack.
- Server operations
What is HPE iLO? Remote management for ProLiant servers explained
HPE iLO (Integrated Lights-Out) is the BMC built into ProLiant servers: a separate chip with its own network port that lets you power the host on and off, see its screen and mount an ISO with nobody on site. What you can do depends on the iLO generation and the license.
- Server operations
What is IP KVM? How KVM over IP works, its three forms and when you need one
What is IP KVM? Hardware that puts a computer's screen, keyboard and mouse on the network: it streams the video output to your browser and feeds your input back as USB. Because it works outside the OS, you can operate POST, the BIOS, installers and blue screens remotely.
- Data center
What is a PDU? Rack power distribution units: role, types and specs
In a data center, PDU stands for power distribution unit: a strip in the rack that splits one upstream circuit across the equipment, adding protection, metering and remote control. In networking, PDU means protocol data unit, which has nothing to do with power.
- Data center
What is PUE? Data center power usage effectiveness explained
PUE (power usage effectiveness) = total data center energy ÷ IT equipment energy. A PUE of 1.5 means each kWh used by IT equipment costs another 0.5 kWh for cooling, power losses and lighting. Closer to 1.0 is better, but PUE only measures how efficiently power reaches IT, not how well IT uses it.
- Server operations
What is PXE boot? How network booting and PXE installs work
PXE (Preboot eXecution Environment) is network booting built into NIC firmware. A server with no OS asks DHCP for an address and a boot file name, downloads a bootloader over TFTP and runs it from memory. A PXE install uses that path to deliver the installer and an answer file, with no USB stick.
- Security & compliance
ARP spoofing attack explained: how it works, what it damages and how to spot it in a data center
An ARP spoofing attack sends forged ARP replies on a layer 2 segment so other hosts map the gateway's or a server's IP to the attacker's MAC. ARP has no authentication, so no exploit is needed; one compromised server can take a whole VLAN down, hijack traffic or steal IPs.
- IDC business & buying guides
How automated server provisioning works: from paid order to delivered server
Automated server provisioning is an order state machine: a payment reserves a free server, then IP assignment, switch port setup, a PXE reinstall over IPMI and credential delivery run in a fixed order. Each step must detect failure and release what it took, or servers stay half-provisioned.
- Data center
19 inch rack standard: what the 482.6 mm width really measures
In the 19 inch rack standard, 19 inches (482.6 mm) is the equipment panel width, not the cabinet. Rail holes are 465.1 mm apart, the opening is 450.85 mm, cabinets are usually 600 or 800 mm wide, and 1U = 44.45 mm with three holes per U.
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