Add DNS support (#516)

* Rename whitelist to allowlist.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Additional updates.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Whitelist renaming.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Address reviewer feedback.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Fix typos.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Add DNS command line options.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Add DNS support.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Address reviewer feedback.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Address reviewer feedback.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

* Fix markdown issue.

Signed-off-by: Byron Gravenorst <byron.gravenorst@consensys.net>

docs/Concepts/Node-Keys.md

@@ -42,6 +42,14 @@ You can export the node address, either to standard output or to a specified fil
 The enode URL identifies a node. For example, the `--bootnodes` option and the
 `perm_addNodesToAllowlist` method specify nodes by enode URL.
 
+!!! tip
+
+    If deploying Besu using Kubernetes in private permissioned networks, use the
+    [`--Xdns-enabled`](../Reference/CLI/CLI-Syntax.md#xdns-enabled) and
+    [`--Xdns-update-enabled`](../Reference/CLI/CLI-Syntax.md#xdns-update-enabled) options to use
+    domain names instead of IP addresses. This ensures that Besu can connect to a container even if
+    the IP address changes after being restarted.
+
 The enode URL format is `enode://<id>@<host:port>` where:
 
 * `<id>` is the node public key, excluding the initial 0x.

docs/HowTo/Limit-Access/Local-Permissioning.md

@@ -6,6 +6,14 @@ description: Hyperledger Besu local permissioning
 
 Local permissioning supports node and account allowlisting.
 
+!!! tip
+
+    If deploying Besu using Kubernetes in private permissioned networks, use the
+    [`--Xdns-enabled`](../../Reference/CLI/CLI-Syntax.md#xdns-enabled) and
+    [`--Xdns-update-enabled`](../../Reference/CLI/CLI-Syntax.md#xdns-update-enabled) options to use
+    domain names instead of IP addresses. This ensures that Besu can connect to a container even if
+    the IP address changes after being restarted.
+
 ## Node allowlisting
 
 You can allow access to specified nodes in the

docs/Reference/CLI/CLI-Syntax.md

@@ -3029,6 +3029,78 @@ The price bump percentage to replace an existing transaction. The default is 10.
 The maximum period, in hours, to hold pending transactions in the transaction pool. The default is
 13.
 
+### Xdns-enabled
+
+=== "Syntax"
+
+    ```bash
+    --Xdns-enabled=[<true|false>]
+    ```
+
+=== "Command Line"
+
+    ```bash
+    --Xdns-enabled=true
+    ```
+
+=== "Environment Variable"
+
+    ```bash
+    BESU_XDNS_ENABLED=true
+    ```
+
+=== "Configuration File"
+
+    ```bash
+    Xdns-enabled=true
+    ```
+
+Enables DNS support. The default is `false`.
+
+!!! important
+
+    Use domain names in private networks only because public networks require using IP addresses.
+    This is an early access feature. Some functionality may be updated before the feature is fully
+    released.
+
+Use DNS with a trusted DNS provider in private networks because of limitations where IP addresses
+can change. For example, when using Kubernetes pods.
+
+### Xdns-update-enabled
+
+=== "Syntax"
+
+    ```bash
+    --Xdns-update-enabled=[<true|false>]
+    ```
+
+=== "Command Line"
+
+    ```bash
+    --Xdns-update-enabled=true
+    ```
+
+=== "Environment Variable"
+
+    ```bash
+    BESU_XDNS_UPDATE_ENABLED=true
+    ```
+
+=== "Configuration File"
+
+    ```bash
+    Xdns-update-enabled=true
+    ```
+
+Allow Besu to continuously query the DNS to ensure updates to IP addresses are automatically
+detected. The default is `false`.
+
+[`Xdns-enabled`](#Xdns-enabled) must be set to `true`.
+
+!!! important
+
+    This is an early access feature. Some functionality may be updated before the feature is fully released.
+
 ### version
 
 === "Syntax"