Dedicated server glossary

A

Anycast

A routing method in which the same IP address is announced from several locations at once, and BGP sends each visitor to the nearest one. DNS services and CDNs use anycast to answer from close by and to spread attack traffic.

ARP

Address Resolution Protocol. On an IPv4 network, it finds the MAC address of the machine that holds a given IP address. IPv6 uses Neighbor Discovery (NDP) for the same job.

ASN

Autonomous System Number: the identifier of a network, such as a hosting provider or an ISP, that exchanges routes with other networks over BGP. mtr -z shows the ASN of each hop.

B

Bandwidth vs throughput

Bandwidth is the capacity of a link, such as a 1 Gbps port. Throughput is the data actually transferred, which is lower because of protocol overhead, latency and the other end of the connection: a 1 Gbps port carries about 940 Mbit/s of TCP payload. See Unmetered bandwidth explained.

Bare metal

A physical server used by a single customer, with no provider hypervisor between the operating system and the hardware. Every DediJet server is bare metal.

BGP

Border Gateway Protocol, which networks use to exchange routes on the internet. Our network is multi-homed with several transit providers over BGP; see Network.

BMC

Baseboard Management Controller: a small independent computer on the motherboard that provides IPMI, including power control, hardware sensors and a remote console, even when the server is switched off.

Burn-in

Stress testing hardware before it goes into service. Every in-stock DediJet server passes a memory test, a CPU stress test and SMART/NVMe health checks before it joins the ready pool; see How instant delivery works.

C

CDN

Content delivery network: caching servers in many locations that deliver content close to visitors and absorb much of the traffic, including application-layer floods, before it reaches your origin server.

Core vs thread

A core is a physical processing unit; with simultaneous multithreading (SMT), each core runs two hardware threads. A 16C/32T processor such as the Ryzen 9 9950X has 16 cores and 32 threads. The second thread adds throughput, but much less than a second core would.

Cross-connect

A physical cable inside a data center that links one party’s equipment directly to another network or customer in the same building.

D

DDoS

Distributed denial of service: an attack in which many machines send traffic to exhaust a target’s bandwidth, connection tables or application. Network-level (L3/L4) mitigation is included with every server; see How DDoS protection works.

DDR5

The fifth generation of DDR memory, used on current AMD Ryzen and EPYC platforms. Its on-die ECC only corrects errors inside the memory chips; end-to-end error correction requires ECC modules, listed as DDR5 ECC.

Dedicated server

A whole physical server rented to one customer: every core, all the memory and the full disk and network capacity are yours. Compare it with a VPS in Dedicated server vs VPS.

E

ECC memory

Error-correcting code memory corrects single-bit errors and detects double-bit errors, preventing silent data corruption and many crashes. Plans listed with DDR4 ECC or DDR5 ECC use it.

F

fio

Flexible I/O Tester, the standard tool for measuring storage performance: IOPS, bandwidth and latency. See Benchmark CPU, memory, disks and network.

G

Gbps

Gigabits per second, the unit of network speed. 1 Gbps is at most 125 MB/s before protocol overhead; 10 Gbps is 1.25 GB/s.

H

HDD

Hard disk drive, with spinning magnetic platters. It offers large capacity at a low cost per terabyte, but far fewer random IOPS than an SSD. Our storage servers combine large HDDs with NVMe drives.

Hot swap

Replacing a component, typically a disk or a power supply, while the server keeps running. Whether a drive can be swapped hot depends on the chassis and its backplane.

Hypervisor

Software that runs virtual machines and shares the hardware between them. Type 1 hypervisors such as KVM (used by Proxmox VE), VMware ESXi and Hyper-V run directly on the hardware.

I

IOPS

Input/output operations per second: how many small reads or writes a disk handles. Only compare IOPS figures measured with the same block size and queue depth.

IPMI

Intelligent Platform Management Interface, the standard for out-of-band management through the BMC. Your dashboard gives you the IPMI console, power control and virtual media; see Use the IPMI/KVM console.

IPv4

The 32-bit internet address format, written like 203.0.113.10. Each server includes one dedicated IPv4 address, and more cost $2.50 per IP per month; see Additional IPv4 addresses.

IPv6

The 128-bit successor of IPv4, written like 2001:db8::1. Every server includes a routed /64 subnet, and a /56 is free on request; see Configure your /64 IPv6 subnet.

IXP

Internet exchange point: a place where many networks connect to exchange traffic directly. Frankfurt, Amsterdam and London are home to some of the largest IXPs in the world.

J

Jitter

The variation in latency from one packet to the next. Low jitter matters for voice, video calls and game servers; mtr shows it as the spread between the best and worst times of each hop.

K

KVM (Linux hypervisor)

Kernel-based Virtual Machine, the virtualization layer built into the Linux kernel. Together with QEMU, it runs the virtual machines in Proxmox VE.

KVM-over-IP

Remote keyboard, video and mouse over the network: you see the server’s screen from power-on and type as if you were in front of it. At DediJet it is part of the IPMI console in your dashboard.

L

L3 cache

The largest, last level of CPU cache, shared between cores. More cache helps games, databases and simulations: for example, 32 MB on a Ryzen 7 9700X and 256 MB on an EPYC 9354P.

Latency

The time a packet takes to travel, usually measured as a round trip (ping). Light in fiber covers about 200 km per millisecond, so distance sets a floor no network can beat. Estimated values for each location are on the latency checker.

Lightning Network

A payment network built on top of Bitcoin that settles payments in seconds with low fees. It is the fastest way to pay a DediJet invoice; see Pay with crypto.

M

mdadm

The Linux tool for creating and managing software RAID arrays. Two-disk DediJet servers get software RAID 1 by default; see Manage software RAID 1 with mdadm.

MTR

A network diagnostic tool that combines traceroute and ping to show loss and latency at every hop. Attach a report (mtr -rwzc 100) when you report a network problem; see Network testing.

N

Null route

Dropping all traffic to one IP address at the router, also called blackholing. It protects the rest of the network but takes the target offline, which is why we filter attacks rather than null-route whenever possible.

NVMe

Non-Volatile Memory Express, the protocol SSDs use over PCIe, with much lower latency and far more parallel queues than SATA. Linux names NVMe drives nvme0n1, nvme1n1 and so on.

P

Packet loss

The share of packets that never arrive. Loss that continues to the last hop of an mtr report is real; loss on a single intermediate hop is usually a router limiting its own ICMP replies.

PCIe

PCI Express, the bus that connects NVMe drives, GPUs and network cards to the CPU. Each generation roughly doubles bandwidth per lane: about 2 GB/s for PCIe 4.0 and 4 GB/s for PCIe 5.0, in each direction.

Peering

Two networks exchanging traffic directly, at an IXP or over a private link, instead of through a paid transit provider. Direct paths often shorten routes and lower latency.

Port speed

The line rate of a server’s network port: 1 Gbps or 10 Gbps on DediJet plans, unmetered. 1 Gbps plans can be upgraded to 10 Gbps for $129 per month; see Add-ons.

Proxmox VE

An open-source virtualization platform based on Debian, with KVM virtual machines, LXC containers, ZFS and a web interface. Proxmox VE 9 is a one-click install; see Install Proxmox VE 9.

PTR record

The DNS record that maps an IP address back to a hostname. Receiving mail servers expect a sending server’s PTR record to match its hostname; see Reverse DNS.

R

Rack unit (U)

The standard unit of rack height: 1U is 1.75 inches (44.45 mm). Servers are described as 1U, 2U and so on.

RAID 0

Striping: data is split across disks for speed and full capacity, with no redundancy. If one disk fails, all data in the array is lost. It can be selected instead of RAID 1 at install time.

RAID 1

Mirroring: every write goes to two disks, so the array survives the failure of one, at the cost of half the raw capacity. It is the default on two-disk DediJet servers, and it is not a backup.

RAID 10

A stripe across mirrored pairs, using four or more disks: the speed of striping with the redundancy of mirroring. Half of the raw capacity is usable.

Rescue mode

A temporary Linux system you start from the dashboard to repair an installed system that no longer boots, reset a password or copy data off. See Rescue mode.

Reverse DNS

Looking up a hostname from an IP address, answered by PTR records. You can set reverse DNS for your addresses in the dashboard, free of charge.

Root access

Full administrative control of the system: root on Linux, Administrator on Windows. Every DediJet server includes it, and servers are unmanaged: you are the administrator.

S

SLA

Service level agreement: the commitments a provider makes and the credits you receive if they are missed. Ours targets 99.9% network availability per calendar month and hardware replacement within 4 hours of diagnosis; see the SLA.

SMART

Self-Monitoring, Analysis and Reporting Technology: health data recorded by the disks themselves, such as reallocated sectors or wear. Read it with smartctl; see Check disk health.

SSD

Solid-state drive: flash storage with no moving parts. SATA SSDs use the older disk interface; NVMe SSDs connect over PCIe and are much faster.

Subnet / CIDR

A block of IP addresses written as a prefix and a length, such as 198.51.100.0/24 (256 addresses). A /29 holds 8 IPv4 addresses and a /28 holds 16, while an IPv6 /64 holds about 18 quintillion.

T

TDP

Thermal design power: the heat, in watts, that a processor’s cooling must remove under sustained load, for example 65 W for a Ryzen 7 9700X and 170 W for a Ryzen 9 9950X. Actual power draw can differ.

Tier (data center)

A classification of data center redundancy from Tier I to Tier IV, defined by the Uptime Institute. Our locations are carrier-neutral data centers with redundant (N+1 or better) power and cooling; see Locations.

Transit

IP transit: a paid service in which a provider carries your traffic to the rest of the internet. Our network is multi-homed with several transit providers. Reselling DediJet bandwidth as transit is not allowed by the acceptable use policy.

U

Unmetered

Traffic is not counted or billed by volume: the limit is the speed of your port, 24/7, within the acceptable use policy. A 1 Gbps unmetered port still moves at most 1 Gbps at any moment.

V

Virtual media

An IPMI feature that mounts an ISO image over the network as if it were a USB or DVD drive in the server, so you can install any operating system yourself, such as TrueNAS or VMware ESXi with your own license.

VLAN

Virtual LAN: a separate network segment on shared switches. A private VLAN between your servers in the same location is free on request.

VPS

Virtual private server: a virtual machine on a host shared with other customers. Less expensive to start with, but CPU, disk and network capacity are shared; see Dedicated server vs VPS.

Z

ZFS

A combined file system and volume manager that checksums every block, repairs errors from redundant copies, and supports snapshots, compression and replication. Popular on Proxmox VE and storage servers, it uses RAM for its ARC cache.