---
name: "hosts"
section: "5"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/hosts"
---

# hosts(5)

host and network name database

## NAME

**hosts** – host and network name database

## DESCRIPTION

The **hosts** file associates names and IP addresses. Each line has the following format:

```
Internet address
Host or network name
Aliases
```

Items are separated by any number of blanks and/or tab characters. A ‘#’ indicates the beginning of a comment; characters up to the end of the line are not interpreted by routines which search the file.

The system configuration file [resolv.conf(5)](/resolv.conf/5.md) controls where host name information will be searched for. The mechanism provided permits the administrator to describe the databases to search; the databases currently known include DNS and the **hosts** database.

When using a name server, this file provides a backup when the name server is not running. For the name server, it is suggested that only a few addresses be included in this file. These include addresses for the local interfaces that [ifconfig(8)](/ifconfig/8.md) needs at boot time and a few machines on the local network.

Internet addresses are specified using either dot notation (IPv4) or colon separated notation (IPv6) as described in [inet\_pton(3)](/inet_pton/3.md). Host names may contain any printable character other than a field delimiter, newline, or comment character.

The host "localhost" and all names underneath the localhost domain will always resolve to the loopback addresses 127.0.0.1 or ::1.

## FILES

- */etc/hosts*

  ## SEE ALSO

[getaddrinfo(3)](/getaddrinfo/3.md), [gethostbyname(3)](/gethostbyname/3.md), [getnameinfo(3)](/getnameinfo/3.md), [inet\_pton(3)](/inet_pton/3.md), [resolv.conf(5)](/resolv.conf/5.md), [ifconfig(8)](/ifconfig/8.md), [nsd(8)](/nsd/8.md), [unbound(8)](/unbound/8.md)

## HISTORY

The **hosts** file format appeared in 4.2BSD.

An official host database used to be maintained at the Network Information Control Center (NIC).

Up to OpenBSD 6.3, a separate file */etc/networks* could be used to store network names.

## BUGS

A name server should be used instead of a static file.

Lines in */etc/hosts* are limited to BUFSIZ characters (currently 1024). Longer lines will be ignored.