diff --git a/.github/regression.sh b/.github/regression.sh
index 4394e7c25..2e3902e94 100755
--- a/.github/regression.sh
+++ b/.github/regression.sh
@@ -13,8 +13,6 @@ df -h .
 
 retval=0
 
-DEFAULT_CLUSTER_ERA="conway"
-
 REPODIR="$(readlink -m "${0%/*}/..")"
 cd "$REPODIR"
 
@@ -55,22 +53,12 @@ if [ -n "${CLUSTERS_COUNT:-}" ]; then
   export CLUSTERS_COUNT
 fi
 
-CLUSTER_ERA="${CLUSTER_ERA:-"$DEFAULT_CLUSTER_ERA"}"
-if [ "$CLUSTER_ERA" = "conway 10" ]; then
-  CLUSTER_ERA="conway"
-elif [ "$CLUSTER_ERA" = "conway 11" ]; then
-  CLUSTER_ERA="conway"
+if [ "${CLUSTER_ERA:-}" = "conway 10" ]; then
+  export CLUSTER_ERA="conway"
+elif [ "${CLUSTER_ERA:-}" = "conway 11" ]; then
+  export CLUSTER_ERA="conway"
   export PROTOCOL_VERSION=11
 fi
-export CLUSTER_ERA
-
-TX_ERA="${TX_ERA:-}"
-if [ "$TX_ERA" = "conway" ] || [ "$CLUSTER_ERA" = "conway" ]; then
-  unset TX_ERA
-  export COMMAND_ERA="conway"
-elif [ "$TX_ERA" = "default" ]; then
-  export TX_ERA=""
-fi
 
 # Decrease the number of tests per cluster if we are using the "disk" (LMDB) UTxO backend to avoid
 # having too many concurrent readers.
@@ -78,12 +66,10 @@ if [ -z "${MAX_TESTS_PER_CLUSTER:-}" ] && [[ "${UTXO_BACKEND:-}" = "disk"* ]]; t
   export MAX_TESTS_PER_CLUSTER=5
 fi
 
-if [ -n "${BOOTSTRAP_DIR:-}" ]; then
-  :  # don't touch `TESTNET_VARIANT` when running on testnet
+if [ -n "${TESTNET_VARIANT:-}" ]; then
+  export TESTNET_VARIANT
 elif [ "${CI_BYRON_CLUSTER:-"false"}" != "false" ]; then
-  export TESTNET_VARIANT="${TESTNET_VARIANT:-"${CLUSTER_ERA}_slow"}"
-else
-  export TESTNET_VARIANT="${TESTNET_VARIANT:-"${CLUSTER_ERA}_fast"}"
+  export TESTNET_VARIANT="${CLUSTER_ERA:-conway}_slow"
 fi
 
 if [ "${ALLOW_UNSTABLE_ERROR_MESSAGES:-"false"}" == "false" ]; then
diff --git a/cardano_node_tests/tests/test_tx_basic.py b/cardano_node_tests/tests/test_tx_basic.py
index edbe50d51..417c0c656 100644
--- a/cardano_node_tests/tests/test_tx_basic.py
+++ b/cardano_node_tests/tests/test_tx_basic.py
@@ -1249,7 +1249,7 @@ def test_far_future_ttl(
     @pytest.mark.parametrize(
         "cluster_default_tx_era",
         (True, False),
-        ids=("explicit_tx_era", "implicit_tx_era"),
+        ids=("explicit_tx_era", "latest_tx_era"),
         indirect=True,
     )
     @pytest.mark.smoke
@@ -1264,8 +1264,8 @@ def test_default_tx_era(
     ):
         """Test default Tx era.
 
-        * check that default Tx era is implicit
-        * check that default Tx era can be specified explicitly
+        * check that default Tx era is implicit as `latest`
+        * check that default Tx era can be specified explicitly by its name
         """
         temp_template = common.get_test_id(cluster)
 
diff --git a/cardano_node_tests/tests/test_tx_negative.py b/cardano_node_tests/tests/test_tx_negative.py
index d2e19cc40..e5b7753a7 100644
--- a/cardano_node_tests/tests/test_tx_negative.py
+++ b/cardano_node_tests/tests/test_tx_negative.py
@@ -36,14 +36,15 @@ class TestNegative:
 
     @pytest.fixture(scope="class")
     def skip_on_last_era(self) -> None:
-        if VERSIONS.cluster_era == VERSIONS.LAST_KNOWN_ERA:
+        last_known_era_name = VERSIONS.MAP[VERSIONS.LAST_KNOWN_PROTOCOL_VERSION]
+        if VERSIONS.cluster_era_name == last_known_era_name:
             pytest.skip(
                 f"doesn't run with the latest cluster era ({VERSIONS.cluster_era_name})",
             )
 
     @pytest.fixture(scope="class")
     def skip_unknown_last_era(self) -> None:
-        last_known_era_name = VERSIONS.MAP[VERSIONS.LAST_KNOWN_ERA]
+        last_known_era_name = VERSIONS.MAP[VERSIONS.LAST_KNOWN_PROTOCOL_VERSION]
         if not clusterlib_utils.cli_has(last_known_era_name):
             pytest.skip(f"`{last_known_era_name} transaction build-raw` command is not available")
 
diff --git a/cardano_node_tests/utils/versions.py b/cardano_node_tests/utils/versions.py
index 3e2f51d7a..a0ec7db2a 100644
--- a/cardano_node_tests/utils/versions.py
+++ b/cardano_node_tests/utils/versions.py
@@ -11,26 +11,36 @@
 class Versions:
     """Cluster era, transaction era, node version info."""
 
+    # Era names for latest corresponding (or current mainnet) protocol version
     BYRON: tp.Final[int] = 1
     SHELLEY: tp.Final[int] = 2
     ALLEGRA: tp.Final[int] = 3
     MARY: tp.Final[int] = 4
     ALONZO: tp.Final[int] = 6
     BABBAGE: tp.Final[int] = 8
-    CONWAY: tp.Final[int] = 9
+    CONWAY: tp.Final[int] = 10
+    DIJKSTRA: tp.Final[int] = 12
 
-    DEFAULT_CLUSTER_ERA: tp.Final[int] = 9
-    DEFAULT_TX_ERA: tp.Final[int] = 9
-    LAST_KNOWN_ERA: tp.Final[int] = 9
+    DEFAULT_CLUSTER_ERA: tp.Final[int] = CONWAY
+    DEFAULT_TX_ERA: tp.Final[int] = DEFAULT_CLUSTER_ERA
+    # Latest protocol version supported by the node
+    LAST_KNOWN_PROTOCOL_VERSION: tp.Final[int] = 11
 
+    # Map protocol versions to era names
     MAP: tp.ClassVar[dict[int, str]] = {
+        0: "byron",
         1: "byron",
         2: "shelley",
         3: "allegra",
         4: "mary",
+        5: "alonzo",
         6: "alonzo",
+        7: "babbage",
         8: "babbage",
         9: "conway",
+        10: "conway",
+        11: "conway",
+        12: "dijkstra",
     }
 
     def __init__(self) -> None: