diff --git a/packages/ripple-binary-codec/src/enums/definitions.json b/packages/ripple-binary-codec/src/enums/definitions.json
index 317e1feb..a59de992 100644
--- a/packages/ripple-binary-codec/src/enums/definitions.json
+++ b/packages/ripple-binary-codec/src/enums/definitions.json
@@ -321,6 +321,16 @@
         "type": "UInt16"
       }
     ],
+    [
+      "NetworkID",
+      {
+        "nth": 1,
+        "isVLEncoded": false,
+        "isSerialized": true,
+        "isSigningField": true,
+        "type": "UInt32"
+      }
+    ],
     [
       "Flags",
       {
@@ -2176,6 +2186,9 @@
     "telCAN_NOT_QUEUE_BLOCKED": -389,
     "telCAN_NOT_QUEUE_FEE": -388,
     "telCAN_NOT_QUEUE_FULL": -387,
+    "telWRONG_NETWORK": -386,
+    "telREQUIRES_NETWORK_ID": -385,
+    "telNETWORK_ID_MAKES_TX_NON_CANONICAL": -384,
 
     "temMALFORMED": -299,
     "temBAD_AMOUNT": -298,
diff --git a/packages/xrpl/src/client/index.ts b/packages/xrpl/src/client/index.ts
index 24bad32f..27b2402e 100644
--- a/packages/xrpl/src/client/index.ts
+++ b/packages/xrpl/src/client/index.ts
@@ -205,6 +205,18 @@ class Client extends EventEmitter {
    */
   public readonly maxFeeXRP: string
 
+  /**
+   * Network ID of the server this client is connected to
+   *
+   */
+  public networkID: number | undefined
+
+  /**
+   * Rippled Version used by the server this client is connected to
+   *
+   */
+  public buildVersion: string | undefined
+
   /**
    * Creates a new Client with a websocket connection to a rippled server.
    *
@@ -230,8 +242,8 @@ class Client extends EventEmitter {
       this.emit('error', errorCode, errorMessage, data)
     })
 
-    this.connection.on('connected', () => {
-      this.emit('connected')
+    this.connection.on('reconnect', () => {
+      this.connection.on('connected', () => this.emit('connected'))
     })
 
     this.connection.on('disconnected', (code: number) => {
@@ -568,6 +580,22 @@ class Client extends EventEmitter {
     return results
   }
 
+  /**
+   * Get networkID and buildVersion from server_info
+   */
+  public async getServerInfo(): Promise<void> {
+    try {
+      const response = await this.request({
+        command: 'server_info',
+      })
+      this.networkID = response.result.info.network_id ?? undefined
+      this.buildVersion = response.result.info.build_version
+    } catch (error) {
+      // eslint-disable-next-line no-console -- Print the error to console but allows client to be connected.
+      console.error(error)
+    }
+  }
+
   /**
    * Tells the Client instance to connect to its rippled server.
    *
@@ -588,7 +616,10 @@ class Client extends EventEmitter {
    * @category Network
    */
   public async connect(): Promise<void> {
-    return this.connection.connect()
+    return this.connection.connect().then(async () => {
+      await this.getServerInfo()
+      this.emit('connected')
+    })
   }
 
   /**
diff --git a/packages/xrpl/src/models/methods/serverInfo.ts b/packages/xrpl/src/models/methods/serverInfo.ts
index a41f3333..97401ccd 100644
--- a/packages/xrpl/src/models/methods/serverInfo.ts
+++ b/packages/xrpl/src/models/methods/serverInfo.ts
@@ -136,6 +136,10 @@ export interface ServerInfoResponse extends BaseResponse {
        * overall network's load factor.
        */
       load_factor?: number
+      /**
+       * The network id of the server.
+       */
+      network_id?: number
       /**
        * Current multiplier to the transaction cost based on
        * load to this server.
diff --git a/packages/xrpl/src/models/transactions/common.ts b/packages/xrpl/src/models/transactions/common.ts
index 59abdebf..cbb7d4a4 100644
--- a/packages/xrpl/src/models/transactions/common.ts
+++ b/packages/xrpl/src/models/transactions/common.ts
@@ -157,6 +157,10 @@ export interface BaseTransaction {
    * account it says it is from.
    */
   TxnSignature?: string
+  /**
+   * The network id of the transaction.
+   */
+  NetworkID?: number
 }
 
 /**
@@ -250,6 +254,9 @@ export function validateBaseTransaction(common: Record<string, unknown>): void {
   ) {
     throw new ValidationError('BaseTransaction: invalid TxnSignature')
   }
+  if (common.NetworkID !== undefined && typeof common.NetworkID !== 'number') {
+    throw new ValidationError('BaseTransaction: invalid NetworkID')
+  }
 }
 
 /**
diff --git a/packages/xrpl/src/sugar/autofill.ts b/packages/xrpl/src/sugar/autofill.ts
index 8e3435ee..82766166 100644
--- a/packages/xrpl/src/sugar/autofill.ts
+++ b/packages/xrpl/src/sugar/autofill.ts
@@ -12,6 +12,13 @@ import getFeeXrp from './getFeeXrp'
 
 // Expire unconfirmed transactions after 20 ledger versions, approximately 1 minute, by default
 const LEDGER_OFFSET = 20
+// Sidechains are expected to have network IDs above this.
+// Networks with ID above this restricted number are expected specify an accurate NetworkID field
+// in every transaction to that chain to prevent replay attacks.
+// Mainnet and testnet are exceptions. More context: https://github.com/XRPLF/rippled/pull/4370
+const RESTRICTED_NETWORKS = 1024
+const REQUIRED_NETWORKID_VERSION = '1.11.0'
+const HOOKS_TESTNET_ID = 21338
 interface ClassicAccountAndTag {
   classicAccount: string
   tag: number | false | undefined
@@ -70,8 +77,10 @@ async function autofill<T extends Transaction>(
   setValidAddresses(tx)
 
   setTransactionFlagsToNumber(tx)
-
   const promises: Array<Promise<void>> = []
+  if (tx.NetworkID == null) {
+    tx.NetworkID = txNeedsNetworkID(this) ? this.networkID : undefined
+  }
   if (tx.Sequence == null) {
     promises.push(setNextValidSequenceNumber(this, tx))
   }
@@ -88,6 +97,101 @@ async function autofill<T extends Transaction>(
   return Promise.all(promises).then(() => tx)
 }
 
+/**
+ * Determines whether the source rippled version is not later than the target rippled version.
+ * Example usage: isNotLaterRippledVersion('1.10.0', '1.11.0') returns true.
+ *                isNotLaterRippledVersion('1.10.0', '1.10.0-b1') returns false.
+ *
+ * @param source -- The source rippled version.
+ * @param target -- The target rippled version.
+ * @returns True if source is earlier than target, false otherwise.
+ */
+// eslint-disable-next-line max-lines-per-function, max-statements -- Disable for this helper functions.
+function isNotLaterRippledVersion(source: string, target: string): boolean {
+  if (source === target) {
+    return true
+  }
+  const sourceDecomp = source.split('.')
+  const targetDecomp = target.split('.')
+  const sourceMajor = parseInt(sourceDecomp[0], 10)
+  const sourceMinor = parseInt(sourceDecomp[1], 10)
+  const targetMajor = parseInt(targetDecomp[0], 10)
+  const targetMinor = parseInt(targetDecomp[1], 10)
+  // Compare major version
+  if (sourceMajor !== targetMajor) {
+    return sourceMajor < targetMajor
+  }
+  // Compare minor version
+  if (sourceMinor !== targetMinor) {
+    return sourceMinor < targetMinor
+  }
+  const sourcePatch = sourceDecomp[2].split('-')
+  const targetPatch = targetDecomp[2].split('-')
+
+  const sourcePatchVersion = parseInt(sourcePatch[0], 10)
+  const targetPatchVersion = parseInt(targetPatch[0], 10)
+
+  // Compare patch version
+  if (sourcePatchVersion !== targetPatchVersion) {
+    return sourcePatchVersion < targetPatchVersion
+  }
+
+  // Compare release version
+  if (sourcePatch.length !== targetPatch.length) {
+    return sourcePatch.length > targetPatch.length
+  }
+
+  if (sourcePatch.length === 2) {
+    // Compare different release types
+    if (!sourcePatch[1][0].startsWith(targetPatch[1][0])) {
+      return sourcePatch[1] < targetPatch[1]
+    }
+    // Compare beta version
+    if (sourcePatch[1].startsWith('b')) {
+      return (
+        parseInt(sourcePatch[1].slice(1), 10) <
+        parseInt(targetPatch[1].slice(1), 10)
+      )
+    }
+    // Compare rc version
+    return (
+      parseInt(sourcePatch[1].slice(2), 10) <
+      parseInt(targetPatch[1].slice(2), 10)
+    )
+  }
+
+  return false
+}
+
+/**
+ * Determine if the transaction required a networkID to be valid.
+ * Transaction needs networkID if later than restricted ID and either the network is hooks testnet
+ * or build version is >= 1.11.0
+ *
+ * @param client -- The connected client.
+ * @returns True if required networkID, false otherwise.
+ */
+function txNeedsNetworkID(client: Client): boolean {
+  if (
+    client.networkID !== undefined &&
+    client.networkID > RESTRICTED_NETWORKS
+  ) {
+    // TODO: remove the buildVersion logic when 1.11.0 is out and widely used.
+    // Issue: https://github.com/XRPLF/xrpl.js/issues/2339
+    if (
+      (client.buildVersion &&
+        isNotLaterRippledVersion(
+          REQUIRED_NETWORKID_VERSION,
+          client.buildVersion,
+        )) ||
+      client.networkID === HOOKS_TESTNET_ID
+    ) {
+      return true
+    }
+  }
+  return false
+}
+
 function setValidAddresses(tx: Transaction): void {
   validateAccountAddress(tx, 'Account', 'SourceTag')
   // eslint-disable-next-line @typescript-eslint/dot-notation -- Destination can exist on Transaction
diff --git a/packages/xrpl/test/client/autofill.test.ts b/packages/xrpl/test/client/autofill.test.ts
index cfb93f2c..65ba0d21 100644
--- a/packages/xrpl/test/client/autofill.test.ts
+++ b/packages/xrpl/test/client/autofill.test.ts
@@ -15,13 +15,32 @@ import {
 } from '../setupClient'
 import { assertRejects } from '../testUtils'
 
+const NetworkID = 1025
 const Fee = '10'
 const Sequence = 1432
 const LastLedgerSequence = 2908734
+const HOOKS_TESTNET_ID = 21338
 
 describe('client.autofill', function () {
   let testContext: XrplTestContext
 
+  async function setupMockRippledVersionAndID(
+    buildVersion: string,
+    networkID: number,
+  ): Promise<void> {
+    await testContext.client.disconnect()
+    rippled.server_info.withNetworkId.result.info.build_version = buildVersion
+    rippled.server_info.withNetworkId.result.info.network_id = networkID
+    testContext.client.connection.on('connected', () => {
+      testContext.mockRippled?.addResponse(
+        'server_info',
+        rippled.server_info.withNetworkId,
+      )
+    })
+
+    await testContext.client.connect()
+  }
+
   beforeEach(async () => {
     testContext = await setupClient()
   })
@@ -32,17 +51,116 @@ describe('client.autofill', function () {
       TransactionType: 'DepositPreauth',
       Account: 'rGWrZyQqhTp9Xu7G5Pkayo7bXjH4k4QYpf',
       Authorize: 'rpZc4mVfWUif9CRoHRKKcmhu1nx2xktxBo',
+      NetworkID,
       Fee,
       Sequence,
       LastLedgerSequence,
     }
     const txResult = await testContext.client.autofill(tx)
 
+    assert.strictEqual(txResult.NetworkID, NetworkID)
     assert.strictEqual(txResult.Fee, Fee)
     assert.strictEqual(txResult.Sequence, Sequence)
     assert.strictEqual(txResult.LastLedgerSequence, LastLedgerSequence)
   })
 
+  it('ignores network ID if missing', async function () {
+    const tx: Payment = {
+      TransactionType: 'Payment',
+      Account: 'XVLhHMPHU98es4dbozjVtdWzVrDjtV18pX8yuPT7y4xaEHi',
+      Amount: '1234',
+      Destination: 'X7AcgcsBL6XDcUb289X4mJ8djcdyKaB5hJDWMArnXr61cqZ',
+      Fee,
+      Sequence,
+      LastLedgerSequence,
+    }
+    testContext.mockRippled!.addResponse('ledger', rippled.ledger.normal)
+
+    const txResult = await testContext.client.autofill(tx)
+
+    assert.strictEqual(txResult.NetworkID, undefined)
+  })
+
+  // NetworkID is required in transaction for network > 1024 and from version 1.11.0 or later.
+  // More context: https://github.com/XRPLF/rippled/pull/4370
+  it('overrides network ID if > 1024 and version is later than 1.11.0', async function () {
+    await setupMockRippledVersionAndID('1.11.1', 1025)
+    const tx: Payment = {
+      TransactionType: 'Payment',
+      Account: 'XVLhHMPHU98es4dbozjVtdWzVrDjtV18pX8yuPT7y4xaEHi',
+      Amount: '1234',
+      Destination: 'X7AcgcsBL6XDcUb289X4mJ8djcdyKaB5hJDWMArnXr61cqZ',
+      Fee,
+      Sequence,
+      LastLedgerSequence,
+    }
+    testContext.mockRippled!.addResponse('ledger', rippled.ledger.normal)
+
+    const txResult = await testContext.client.autofill(tx)
+
+    assert.strictEqual(txResult.NetworkID, 1025)
+  })
+
+  // NetworkID is only required in transaction for version 1.11.0 or later.
+  // More context: https://github.com/XRPLF/rippled/pull/4370
+  it('ignores network ID if > 1024 but version is earlier than 1.11.0', async function () {
+    await setupMockRippledVersionAndID('1.10.0', 1025)
+    const tx: Payment = {
+      TransactionType: 'Payment',
+      Account: 'XVLhHMPHU98es4dbozjVtdWzVrDjtV18pX8yuPT7y4xaEHi',
+      Amount: '1234',
+      Destination: 'X7AcgcsBL6XDcUb289X4mJ8djcdyKaB5hJDWMArnXr61cqZ',
+      Fee,
+      Sequence,
+      LastLedgerSequence,
+    }
+    testContext.mockRippled!.addResponse('ledger', rippled.ledger.normal)
+
+    const txResult = await testContext.client.autofill(tx)
+
+    assert.strictEqual(txResult.NetworkID, undefined)
+  })
+
+  // NetworkID <= 1024 does not require a newtorkID in transaction.
+  // More context: https://github.com/XRPLF/rippled/pull/4370
+  it('ignores network ID if <= 1024', async function () {
+    await setupMockRippledVersionAndID('1.11.1', 1023)
+    const tx: Payment = {
+      TransactionType: 'Payment',
+      Account: 'XVLhHMPHU98es4dbozjVtdWzVrDjtV18pX8yuPT7y4xaEHi',
+      Amount: '1234',
+      Destination: 'X7AcgcsBL6XDcUb289X4mJ8djcdyKaB5hJDWMArnXr61cqZ',
+      Fee,
+      Sequence,
+      LastLedgerSequence,
+    }
+    testContext.mockRippled!.addResponse('ledger', rippled.ledger.normal)
+
+    const txResult = await testContext.client.autofill(tx)
+
+    assert.strictEqual(txResult.NetworkID, undefined)
+  })
+
+  // Hooks Testnet requires networkID in transaction regardless of version.
+  // More context: https://github.com/XRPLF/rippled/pull/4370
+  it('overrides network ID for hooks testnet', async function () {
+    await setupMockRippledVersionAndID('1.10.1', HOOKS_TESTNET_ID)
+    const tx: Payment = {
+      TransactionType: 'Payment',
+      Account: 'XVLhHMPHU98es4dbozjVtdWzVrDjtV18pX8yuPT7y4xaEHi',
+      Amount: '1234',
+      Destination: 'X7AcgcsBL6XDcUb289X4mJ8djcdyKaB5hJDWMArnXr61cqZ',
+      Fee,
+      Sequence,
+      LastLedgerSequence,
+    }
+    testContext.mockRippled!.addResponse('ledger', rippled.ledger.normal)
+
+    const txResult = await testContext.client.autofill(tx)
+
+    assert.strictEqual(txResult.NetworkID, HOOKS_TESTNET_ID)
+  })
+
   it('converts Account & Destination X-address to their classic address', async function () {
     const tx: Payment = {
       TransactionType: 'Payment',
diff --git a/packages/xrpl/test/createMockRippled.ts b/packages/xrpl/test/createMockRippled.ts
index 2bae9c17..bae75b6b 100644
--- a/packages/xrpl/test/createMockRippled.ts
+++ b/packages/xrpl/test/createMockRippled.ts
@@ -10,7 +10,7 @@ import type {
 
 import { destroyServer, getFreePort } from './testUtils'
 
-function createResponse(
+export function createResponse(
   request: { id: number | string },
   response: Record<string, unknown>,
 ): string {
diff --git a/packages/xrpl/test/fixtures/rippled/index.ts b/packages/xrpl/test/fixtures/rippled/index.ts
index 757f8fa0..1d48f12c 100644
--- a/packages/xrpl/test/fixtures/rippled/index.ts
+++ b/packages/xrpl/test/fixtures/rippled/index.ts
@@ -12,6 +12,7 @@ import iouPartialPayment from './partialPaymentIOU.json'
 import xrpPartialPayment from './partialPaymentXRP.json'
 import normalServerInfo from './serverInfo.json'
 import highLoadFactor from './serverInfoHighLoadFactor.json'
+import withNetworkIDServerInfo from './serverInfoNetworkID.json'
 import consensusStream from './streams/consensusPhase.json'
 import ledgerStream from './streams/ledger.json'
 import manifestStream from './streams/manifest.json'
@@ -84,6 +85,7 @@ const ledger_data = {
 const server_info = {
   normal: normalServerInfo,
   highLoadFactor,
+  withNetworkId: withNetworkIDServerInfo,
 }
 
 const tx = {
diff --git a/packages/xrpl/test/fixtures/rippled/serverInfoNetworkID.json b/packages/xrpl/test/fixtures/rippled/serverInfoNetworkID.json
new file mode 100644
index 00000000..2d9e45c4
--- /dev/null
+++ b/packages/xrpl/test/fixtures/rippled/serverInfoNetworkID.json
@@ -0,0 +1,31 @@
+{
+  "id": 0,
+  "status": "success",
+  "type": "response",
+  "result": {
+    "info": {
+      "build_version": "1.11.0-rc2",
+      "complete_ledgers": "37621036-38327626",
+      "hostid": "JANE",
+      "io_latency_ms": 1,
+      "last_close": {
+        "converge_time_s": 2,
+        "proposers": 6
+      },
+      "load_factor": 1,
+      "network_id": 1,
+      "peers": 113,
+      "pubkey_node": "n9L6MAkAvZKakewLSJPkCKLxuSQ9jrYXJBd2L4fouhpXauyFh6ZM",
+      "server_state": "full",
+      "validated_ledger": {
+        "age": 0,
+        "base_fee_xrp": 0.00001,
+        "hash": "A219F66BB8C9992E80A3C93A5EA408CD54B8F47F2AC1246C271C495F833752BA",
+        "reserve_base_xrp": 10,
+        "reserve_inc_xrp": 2,
+        "seq": 38327626
+      },
+      "validation_quorum": 5
+    }
+  }
+}
diff --git a/packages/xrpl/test/mockRippledTest.test.ts b/packages/xrpl/test/mockRippledTest.test.ts
index 1c6f717e..f18d1a17 100644
--- a/packages/xrpl/test/mockRippledTest.test.ts
+++ b/packages/xrpl/test/mockRippledTest.test.ts
@@ -22,7 +22,7 @@ describe('mock rippled tests', function () {
     }
 
     await assertRejects(
-      testContext.client.request({ command: 'server_info' }),
+      testContext.client.request({ command: 'account_info' }),
       RippledError,
     )
   })
diff --git a/packages/xrpl/test/models/baseTransaction.test.ts b/packages/xrpl/test/models/baseTransaction.test.ts
index c21a387d..e3aa7af7 100644
--- a/packages/xrpl/test/models/baseTransaction.test.ts
+++ b/packages/xrpl/test/models/baseTransaction.test.ts
@@ -232,4 +232,17 @@ describe('BaseTransaction', function () {
       'BaseTransaction: invalid Memos',
     )
   })
+
+  it(`Handles invalid NetworkID`, function () {
+    const invalidNetworkID = {
+      Account: 'r97KeayHuEsDwyU1yPBVtMLLoQr79QcRFe',
+      TransactionType: 'Payment',
+      NetworkID: '1024',
+    }
+    assert.throws(
+      () => validateBaseTransaction(invalidNetworkID),
+      ValidationError,
+      'BaseTransaction: invalid NetworkID',
+    )
+  })
 })
diff --git a/packages/xrpl/test/setupClient.ts b/packages/xrpl/test/setupClient.ts
index 08ec1e91..5cd9a0af 100644
--- a/packages/xrpl/test/setupClient.ts
+++ b/packages/xrpl/test/setupClient.ts
@@ -5,6 +5,7 @@ import BroadcastClient from '../src/client/BroadcastClient'
 import createMockRippled, {
   type MockedWebSocketServer,
 } from './createMockRippled'
+import rippled from './fixtures/rippled'
 import { destroyServer, getFreePort } from './testUtils'
 
 export interface XrplTestContext {
@@ -29,6 +30,10 @@ async function setupMockRippledConnection(
   context.client.on('error', () => {
     // We must have an error listener attached for reconnect errors
   })
+  context.mockRippled?.addResponse(
+    'server_info',
+    rippled.server_info.withNetworkId,
+  )
 
   return context.client.connect().then(() => context)
 }