# IP addresses & reverse DNS

> Allocate additional IPv4 and IPv6 addresses, move them between servers and set PTR records.

Source: https://docs.avenlith.com/en/ip-addresses  
Category: Networking  
Last updated: 2026-09-22

## What is included

Every server includes one public IPv4 address and a routed /64 IPv6 subnet. Additional IPv4 addresses cost €2.50 per month; subnets from /29 to /24 are available for dedicated servers.

## Floating IPs

A floating IP can be reassigned to another server in the same region in under a second — the basis for simple active/passive failover.

```bash
avenlith ip allocate --region ist1 --type ipv4
avenlith ip assign 203.0.113.50 --server web-01
avenlith ip rdns set 203.0.113.50 mail.example.com
```

Add the address to the operating system as a /32:

```yaml
network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - 203.0.113.24/32
        - 203.0.113.50/32
        - 2a0f:9400:7a00::1/64
```

## Reverse DNS

Set a PTR record for each address you send e-mail from. The forward (A/AAAA) record must point to the same address, otherwise the change is rejected.

> **Note:** > Outgoing SMTP (port 25) is blocked on new cloud accounts to protect our IP reputation. Request unblocking in **Support → Service requests** after your first invoice.