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I don't think it has a size limit in terms of number of lines.

Before DNS, it was this file that served as the only means for doing host name lookups, so I presume that means that the file should be able to have thousands or at least hundreds of entries.

Here's an example from 1985 (the format has changed somewhat): http://jim.rees.org/apollo-archive/hosts.txt This file has 1680 lines out of which 1325 are host lines. The remaining 355 lines are blank, comments, networks or gateways¹.

The only real limit that I could find was that on some systems, the individual lines are limited to less than BUFSIZ characters (1024 on my OpenBSD machine).

If you have more than a couple of handfuls of entries in /etc/hosts, you should consider setting up a local name server instead, but that's my personal opinion.

¹ _{Thanks to Jeff Schaller for digging this up.}

I don't think it has a size limit in terms of number of lines.

Before DNS (which was brought into use in 1985), it was this file that served as the only means for doing host name lookups, so I presume that this means that the file should be able to have thousands or at least hundreds of entries to be able to support the most well-connected pre-1985 Internet nodes.

Here's an example from 1985 (the format has changed somewhat): http://jim.rees.org/apollo-archive/hosts.txt This file has 1680 lines out of which 1325 are host lines. The remaining 355 lines are blank, comments, networks or gateways¹.

The only real limit that I could find was that on some systems, the individual lines are limited to less than BUFSIZ characters (1024 on my OpenBSD machine).

If you have more than a couple of handfuls of entries in /etc/hosts, you should consider setting up a local name server instead, but that's my personal opinion.

¹ _{Thanks to Jeff Schaller for digging this up.}

I don't think it has a size limit in terms of number of lines.

Before DNS, it was this file that served as the only means for doing host name lookups, so I presume that means that the file should be able to have thousands or at least hundreds of entries.

Here's an example from 1985 (the format has changed somewhat): http://jim.rees.org/apollo-archive/hosts.txt This file has 1680 lines out of which 1325 are host lines. The remaining 355 lines are blank, comments, networks or gateways.

The only real limit that I could find was that on some systems, the individual lines are limited to less than BUFSIZ characters (1024 on my OpenBSD machine).

If you have more than a couple of handfuls of entries in /etc/hosts, you should consider setting up a local name server instead, but that's my personal opinion.

I don't think it has a size limit in terms of number of lines.

Before DNS, it was this file that served as the only means for doing host name lookups, so I presume that means that the file should be able to have thousands or at least hundreds of entries.

Here's an example from 1985 (the format has changed somewhat): http://jim.rees.org/apollo-archive/hosts.txt This file has 1680 lines out of which 1325 are host lines. The remaining 355 lines are blank, comments, networks or gateways¹.

The only real limit that I could find was that on some systems, the individual lines are limited to less than BUFSIZ characters (1024 on my OpenBSD machine).

If you have more than a couple of handfuls of entries in /etc/hosts, you should consider setting up a local name server instead, but that's my personal opinion.

¹ _{Thanks to Jeff Schaller for digging this up.}

I don't think it has a size limit in terms of number of lines. Before DNS, it was this file that served as the only means for doing host name lookups, so I presume that means that the file should be able to have thousands or at least hundreds of entries.

The only real limit that I could find was that on some systems, the individual lines are limited to less than BUFSIZ characters (1024 on my OpenBSD machine).

If you have more than a couple of handfuls of entries in /etc/hosts, you should consider setting up a local name server instead, but that's my personal opinion.

I don't think it has a size limit in terms of number of lines. 

Before DNS, it was this file that served as the only means for doing host name lookups, so I presume that means that the file should be able to have thousands or at least hundreds of entries.

Here's an example from 1985 (the format has changed somewhat): http://jim.rees.org/apollo-archive/hosts.txt This file has 1680 lines out of which 1325 are host lines. The remaining 355 lines are blank, comments, networks or gateways.

The only real limit that I could find was that on some systems, the individual lines are limited to less than BUFSIZ characters (1024 on my OpenBSD machine).

If you have more than a couple of handfuls of entries in /etc/hosts, you should consider setting up a local name server instead, but that's my personal opinion.