Where is bind cache file

This type of server is also known as a resolver because it handles recursive queries and generally can handle the grunt work of tracking down DNS data from other servers. The cache can then be used as a source for subsequent requests in order to speed up the total round-trip time. These make up for the lack of adequate DNS resolver libraries implemented on most client machines. A caching DNS server is a good choice for many situations. If it is in close physical proximity to the client machines, it is also very likely to improve the DNS query times.

The second configuration that we will be demonstrating is a forwarding DNS server. However, it actually does none of the recursive querying itself. Instead, it forwards all requests to an outside resolving server and then caches the results to use for later queries. This lets the forwarding server respond from its cache, while not requiring it to do all of the work of recursive queries.

This allows the server to only make single requests the forwarded client request instead of having to go through the entire recursion routine. This may be an advantage in environments where external bandwidth transfer is costly, where your caching servers might need to be changed often, or when you wish to forward local queries to one server and external queries to another server.

Regardless of which configuration choice you wish to use, the first step in implementing a Bind DNS server is to install the actual software. We will also include the documentation and some common utilities:. Now that the Bind components are installed, we can begin to configure the server. The forwarding server will use the caching server configuration as a jumping off point, so regardless of your end goal, configure the server as a Caching server first. First, we will cover how to configure Bind to act as a caching DNS server.

This configuration will force the server to recursively seek answers from other DNS servers when a client issues a query. This means that it is doing the work of querying each related DNS server in turn until it finds the entire response. Move into that directory now:. We are not going to be concerned with the majority of the files in this directory. The main configuration file is called named.

This file simply sources the named. For a caching DNS server, we will only be modifying the named. Open this in your text editor with sudo privileges:. As a DNS server that will be used to resolve recursive queries, we do not want the DNS server to be abused by malicious users. An attack called a DNS amplification attack is especially troublesome because it can cause your server to participate in distributed denial of service attacks. A DNS amplification attack is one way that malicious users try to take down servers or sites on the internet.

To do so, they try to find public DNS servers that will resolve recursive queries. In doing so, the DNS server responds to a small request with a large payload directed at the victims server, effectively amplifying the available bandwidth of the attacker. Hosting a public, recursive DNS server requires a great deal of special configuration and administration. To avoid the possibility of your server being used for malicious purposes, we will configure a list of IP addresses or network ranges that we trust.

Above the options block, we will create a new block called acl. Create a label for the ACL group that you are configuring. In this guide, we will call the group goodclients. We will also add localhost and localnets which will attempt to do this automatically:. Now that we have an ACL of clients that we want to resolve request for, we can configure those capabilities in the options block. Within this block, add the following lines:. We explicitly turned recursion on, and then configured the allow-query parameter to use our ACL specification.

We could have used a different parameter, like allow-recursion to reference our ACL group. If present and recursion is on, allow-recursion will dictate the list of clients that can use recursive services. However, if allow-recursion is not set, then Bind falls back on the allow-query-cache list, then the allow-query list, and finally a default of localnets and localhost only.

We are using it because it is the most general way of specifying the ACL. This is actually all that is required for a caching DNS server. If you decided that this is the server type you wish to use, feel free to skip ahead to learn how to check your configuration files, restart the service, and implement client configurations.

If a forwarding DNS server is a better fit for your infrastructure, we can easily set that up instead. We will start with the configuration that we left off in the caching server configuration. The named. However, we need to change the configuration so that the server no longer attempts to perform recursive queries itself. This will be the location where it gets saved.

And the user bind must have write permission for that directory. I think a view is more like an alternative server configuration for a client set. Effectively, it is a dns virtualhost. For example in named. Marek Lisiecki Marek Lisiecki 21 1 1 bronze badge. What I had to do to view the dump.

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Related 0. Hot Network Questions. The first category is, as its name indicates the default category that is usually assigned to syslog. All categories not mentioned, are similar to the default category.

For a list of the different categories, see the bind9 administrator reference manual. In terms of blade-servers, it ignores all the logs associated with them. The first is dedicated to name resolution, in our case, it is the file db. The second will be used for reverse name resolution, it is the file db. IN MX 10 sid. Once this time expires, it is necessary to recheck the data. Types : SOA : Show romanization to define information about the area.

In this case the name of the primary DNS server "sid. It is composed of several fields: 1. Serial : is the whole non-signed 32 bits. This is the serial number to increment with each change of file. It allows the secondary server to reload the information they have. Refresh : defines the data refresh period.