diff --git a/codexcrawler/application.nim b/codexcrawler/application.nim
index c906b03..8f34113 100644
--- a/codexcrawler/application.nim
+++ b/codexcrawler/application.nim
@@ -109,7 +109,8 @@ proc initializeDht(app: Application): Future[?!void] {.async.} =
   return success()
 
 proc initializeCrawler(app: Application): Future[?!void] {.async.} =
-  app.crawler = Crawler.new(app.dht, app.todoNodes, app.okNodes, app.nokNodes)
+  app.crawler =
+    Crawler.new(app.dht, app.todoNodes, app.okNodes, app.nokNodes, app.config)
   return await app.crawler.start()
 
 proc initializeApp(app: Application): Future[?!void] {.async.} =
diff --git a/codexcrawler/config.nim b/codexcrawler/config.nim
index 20b6554..1c1f041 100644
--- a/codexcrawler/config.nim
+++ b/codexcrawler/config.nim
@@ -10,7 +10,7 @@ let doc =
 Codex Network Crawler. Generates network metrics.
 
 Usage:
-  codexcrawler [--logLevel=<l>] [--publicIp=<a>] [--metricsAddress=<ip>] [--metricsPort=<p>] [--dataDir=<dir>] [--discoveryPort=<p>] [--bootNodes=<n>]
+  codexcrawler [--logLevel=<l>] [--publicIp=<a>] [--metricsAddress=<ip>] [--metricsPort=<p>] [--dataDir=<dir>] [--discoveryPort=<p>] [--bootNodes=<n>] [--stepDelay=<ms>] [--revisitDelay=<m>]
 
 Options:
   --logLevel=<l>          Sets log level [default: TRACE]
@@ -20,6 +20,8 @@ Options:
   --dataDir=<dir>         Directory for storing data [default: crawler_data]
   --discoveryPort=<p>     Port used for DHT [default: 8090]
   --bootNodes=<n>         Semi-colon-separated list of Codex bootstrap SPRs [default: testnet_sprs]
+  --stepDelay=<ms>        Delay in milliseconds per crawl step [default: 1000]
+  --revisitDelay=<m>      Delay in minutes after which a node can be revisited [default: 1440] (24h)
 """
 
 import strutils
@@ -33,12 +35,15 @@ type CrawlerConfig* = ref object
   dataDir*: string
   discPort*: Port
   bootNodes*: seq[SignedPeerRecord]
+  stepDelayMs*: int
+  revisitDelayMins*: int
 
 proc `$`*(config: CrawlerConfig): string =
   "CrawlerConfig:" & " logLevel=" & config.logLevel & " publicIp=" & config.publicIp &
     " metricsAddress=" & $config.metricsAddress & " metricsPort=" & $config.metricsPort &
     " dataDir=" & config.dataDir & " discPort=" & $config.discPort & " bootNodes=" &
-    config.bootNodes.mapIt($it).join(";")
+    config.bootNodes.mapIt($it).join(";") & " stepDelay=" & $config.stepDelayMs &
+    " revisitDelay=" & $config.revisitDelayMins
 
 proc getDefaultTestnetBootNodes(): seq[string] =
   @[
@@ -51,7 +56,7 @@ proc getDefaultTestnetBootNodes(): seq[string] =
     "spr:CiUIAhIhAntGLadpfuBCD9XXfiN_43-V3L5VWgFCXxg4a8uhDdnYEgIDARo8CicAJQgCEiECe0Ytp2l-4EIP1dd-I3_jf5XcvlVaAUJfGDhry6EN2dgQsIufsAYaCwoJBNEmoCiRAnV2KkYwRAIgXO3bzd5VF8jLZG8r7dcLJ_FnQBYp1BcxrOvovEa40acCIDhQ14eJRoPwJ6GKgqOkXdaFAsoszl-HIRzYcXKeb7D9",
     "spr:CiUIAhIhA2AEPzVj1Z_pshWAwvTp0xvRZTigIkYphXGZdiYGmYRwEgIDARo8CicAJQgCEiEDYAQ_NWPVn-myFYDC9OnTG9FlOKAiRimFcZl2JgaZhHAQvKCXugYaCwoJBES3CuORAnd-KkYwRAIgNwrc7n8A107pYUoWfJxL8X0f-flfUKeA6bFrjVKzEo0CID_0q-KO5ZAGf65VsK-d9rV3S0PbFg7Hj3Cv4aVX2Lnn",
     "spr:CiUIAhIhAuhggJhkjeRoR7MHjZ_L_naZKnjF541X0GXTI7LEwXi_EgIDARo8CicAJQgCEiEC6GCAmGSN5GhHsweNn8v-dpkqeMXnjVfQZdMjssTBeL8Qop2quwYaCwoJBJK-4V-RAncuKkYwRAIgaXWoxvKkzrjUZ5K_ayQHKNlYhUEzBXhGviujxfJiGXkCICbsYFivi6Ny1FT6tbofVBRj7lnaR3K9_3j5pUT4862k",
-    "spr:CiUIAhIhA-pnA5sLGDVbqEXsRxDUjQEpiSAximHNbyqr2DwLmTq8EgIDARo8CicAJQgCEiED6mcDmwsYNVuoRexHENSNASmJIDGKYc1vKqvYPAuZOrwQyrekvAYaCwoJBIDHOw-RAnc4KkcwRQIhAJtKNeTykcE5bkKwe-vhSmqyBwc2AnexqFX1tAQGLQJ4AiBJOPseqvI3PyEM8l3hY3zvelZU9lT03O7MA_8cUfF4Uw"
+    "spr:CiUIAhIhA-pnA5sLGDVbqEXsRxDUjQEpiSAximHNbyqr2DwLmTq8EgIDARo8CicAJQgCEiED6mcDmwsYNVuoRexHENSNASmJIDGKYc1vKqvYPAuZOrwQyrekvAYaCwoJBIDHOw-RAnc4KkcwRQIhAJtKNeTykcE5bkKwe-vhSmqyBwc2AnexqFX1tAQGLQJ4AiBJOPseqvI3PyEM8l3hY3zvelZU9lT03O7MA_8cUfF4Uw",
   ]
 
 proc getBootNodeStrings(input: string): seq[string] =
@@ -90,4 +95,6 @@ proc parseConfig*(): CrawlerConfig =
     dataDir: get("--dataDir"),
     discPort: Port(parseInt(get("--discoveryPort"))),
     bootNodes: getBootNodes(get("--bootNodes")),
+    stepDelayMs: parseInt(get("--stepDelay")),
+    revisitDelayMins: parseInt(get("--revisitDelay")),
   )
diff --git a/codexcrawler/crawler.nim b/codexcrawler/crawler.nim
index c3b8124..97f98f2 100644
--- a/codexcrawler/crawler.nim
+++ b/codexcrawler/crawler.nim
@@ -6,6 +6,7 @@ import pkg/questionable/results
 import ./dht
 import ./list
 import ./nodeentry
+import ./config
 
 import std/sequtils
 
@@ -14,6 +15,7 @@ logScope:
 
 type Crawler* = ref object
   dht: Dht
+  config: CrawlerConfig
   todoNodes: List
   okNodes: List
   nokNodes: List
@@ -32,7 +34,7 @@ proc handleNodeOk(c: Crawler, target: NodeEntry) {.async.} =
     error "Failed to add OK-node to list", err = err.msg
 
 proc addNewTodoNode(c: Crawler, nodeId: NodeId): Future[?!void] {.async.} =
-  let entry = NodeEntry(id: nodeId, value: "todo")
+  let entry = NodeEntry(id: nodeId, lastVisit: 0)
   return await c.todoNodes.add(entry)
 
 proc addNewTodoNodes(c: Crawler, newNodes: seq[Node]) {.async.} =
@@ -46,10 +48,10 @@ proc step(c: Crawler) {.async.} =
     ok = $c.okNodes.len
     nok = $c.nokNodes.len
 
-  without target =? (await c.todoNodes.pop()), err:
+  without var target =? (await c.todoNodes.pop()), err:
     error "Failed to get todo node", err = err.msg
 
-  # todo: update target timestamp
+  target.lastVisit = Moment.now().epochSeconds.uint64
 
   without receivedNodes =? (await c.dht.getNeighbors(target.id)), err:
     trace "Call failed", node = $target.id, err = err.msg
@@ -66,7 +68,7 @@ proc worker(c: Crawler) {.async.} =
   try:
     while true:
       await c.step()
-      await sleepAsync(3.secs)
+      await sleepAsync(c.config.stepDelayMs.millis)
   except Exception as exc:
     error "Exception in crawler worker", msg = exc.msg
     quit QuitFailure
@@ -85,6 +87,13 @@ proc start*(c: Crawler): Future[?!void] {.async.} =
   return success()
 
 proc new*(
-    T: type Crawler, dht: Dht, todoNodes: List, okNodes: List, nokNodes: List
+    T: type Crawler,
+    dht: Dht,
+    todoNodes: List,
+    okNodes: List,
+    nokNodes: List,
+    config: CrawlerConfig,
 ): Crawler =
-  Crawler(dht: dht, todoNodes: todoNodes, okNodes: okNodes, nokNodes: nokNodes)
+  Crawler(
+    dht: dht, todoNodes: todoNodes, okNodes: okNodes, nokNodes: nokNodes, config: config
+  )
diff --git a/codexcrawler/list.nim b/codexcrawler/list.nim
index e083e1a..2ce16d3 100644
--- a/codexcrawler/list.nim
+++ b/codexcrawler/list.nim
@@ -30,19 +30,12 @@ type
     onMetric: OnUpdateMetric
 
 proc encode(s: NodeEntry): seq[byte] =
-  ($s.id & ";" & s.value).toBytes()
+  s.toBytes()
 
 proc decode(T: type NodeEntry, bytes: seq[byte]): ?!T =
-  let s = string.fromBytes(bytes)
-  if s.len == 0:
-    return success(NodeEntry(id: NodeId("0".u256), value: ""))
-
-  let tokens = s.split(";")
-  if tokens.len != 2:
-    return failure("expected 2 tokens")
-
-  let id = UInt256.fromHex(tokens[0])
-  success(NodeEntry(id: id, value: tokens[1]))
+  if bytes.len < 1:
+    return success(NodeEntry(id: UInt256.fromHex("0"), lastVisit: 0.uint64))
+  return NodeEntry.fromBytes(bytes)
 
 proc saveItem(this: List, item: NodeEntry): Future[?!void] {.async.} =
   without itemKey =? Key.init(this.name / $item.id), err:
@@ -67,7 +60,7 @@ proc load*(this: List): Future[?!void] {.async.} =
       return failure(err)
     without value =? item.value, err:
       return failure(err)
-    if value.value.len > 0:
+    if value.id > 0 or value.lastVisit > 0:
       this.items.add(value)
 
   this.onMetric(this.items.len.int64)
diff --git a/codexcrawler/nodeentry.nim b/codexcrawler/nodeentry.nim
index a6cc76b..e5b6721 100644
--- a/codexcrawler/nodeentry.nim
+++ b/codexcrawler/nodeentry.nim
@@ -3,10 +3,33 @@ import pkg/stew/endians2
 import pkg/questionable
 import pkg/questionable/results
 import pkg/codexdht
+import pkg/chronos
+import pkg/libp2p
 
 type NodeEntry* = object
   id*: NodeId
-  value*: string # todo: will be last-checked timestamp
+  lastVisit*: uint64
 
 proc `$`*(entry: NodeEntry): string =
-  $entry.id & ":" & entry.value
+  $entry.id & ":" & $entry.lastVisit
+
+proc toBytes*(entry: NodeEntry): seq[byte] =
+  var buffer = initProtoBuffer()
+  buffer.write(1, $entry.id)
+  buffer.write(2, entry.lastVisit)
+  buffer.finish()
+  return buffer.buffer
+
+proc fromBytes*(_: type NodeEntry, data: openArray[byte]): ?!NodeEntry =
+  var
+    buffer = initProtoBuffer(data)
+    idStr: string
+    lastVisit: uint64
+
+  if buffer.getField(1, idStr).isErr:
+    return failure("Unable to decode `idStr`")
+
+  if buffer.getField(2, lastVisit).isErr:
+    return failure("Unable to decode `lastVisit`")
+
+  return success(NodeEntry(id: UInt256.fromHex(idStr), lastVisit: lastVisit))